{"elementGlobalId":100922,"circumscripConfidence":{"id":1,"circumscripConfidenceDescEn":"1 - Strong","circumscripConfidenceDescEs":"1 - Fuerte","circumscripConfidenceDescFr":"1 – Forte"},"classificationLevel":{"id":7,"classificationLevelNameEn":"Species","classificationLevelNameEs":"Especies","classificationLevelNameFr":"Espèce"},"classificationStatus":{"id":1,"classificationStatusDescEn":"Standard","classificationStatusDescEs":"Estándar","classificationStatusDescFr":"Standard"},"iucn":{"id":11,"iucnDescEn":"Least concern","iucnDescEs":"Menos preocupante","iucnDescFr":"Moins préoccupante","iucnCode":"LC"},"nameCategory":{"id":1,"nameCategoryDescEn":"Vertebrate Animal","nameCategoryDescEs":"Animal vertebrado","nameCategoryDescFr":"Animal vertébré","nameTypeCd":"A","nameTypeDesc":"Zoological"},"rankMethodUsed":{"id":4,"rankMethodUsedDescEn":"Expertise without calculation","rankMethodUsedDescEs":null,"rankMethodUsedDescFr":null,"rankMethodUsedExternalDescEn":"Ranked by inspection","rankMethodUsedExternalDescEs":null,"rankMethodUsedExternalDescFr":null},"formattedScientificName":"<i>Castor canadensis</i>","scientificName":"Castor canadensis","scientificNameAuthor":"Kuhl, 1820","primaryCommonName":"American Beaver","relatedItisNames":"<i>Castor canadensis</i> Kuhl, 1820 (TSN 180212)","uniqueId":"ELEMENT_GLOBAL.2.100922","elcode":"AMAFE01010","conceptRefFullCitation":"Wilson, D. E., and D. M. Reeder (editors). 2005. Mammal species of the world: a taxonomic and geographic reference. Third edition. The Johns Hopkins University Press, Baltimore. Two volumes. 2,142 pp. [As modified by ASM the Mammal Diversity Database (MDD) at https://www.mammaldiversity.org/index.html]","conceptName":"<i>Castor canadensis</i>","taxonomicComments":null,"roundedGRank":"G5","conservationStatusFactorsEditionDate":"1995-05-03","conservationStatusFactorsEditionAuthors":null,"primaryCommonNameLanguage":"EN","recordType":"SPECIES","elementNationals":[{"elementNationalId":167704,"classifConfidence":null,"nation":{"id":225,"nameEn":"United States","nameEs":"Estados Unidos","nameFr":"États-Unis","isoCode":"US","region":"United States"},"roundedNRank":"N5","elementSubnationals":[{"elementSubnationalId":296771,"subnation":{"id":45,"nameEn":"Pennsylvania","nameEs":"Pennsylvania","nameFr":"Pennsylvanie","subnationCode":"PA","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":296771,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":402942,"subnation":{"id":22,"nameEn":"Kentucky","nameEs":"Kentucky","nameFr":"Kentucky","subnationCode":"KY","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":402942,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":302553,"subnation":{"id":39,"nameEn":"New Mexico","nameEs":"Nuevo México","nameFr":"Nouveau-Mexique","subnationCode":"NM","dnationId":225},"roundedSRank":"S3","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S3","speciesSubnational":{"elementSubnationalId":302553,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":319838,"subnation":{"id":21,"nameEn":"Kansas","nameEs":"Kansas","nameFr":"Kansas","subnationCode":"KS","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":319838,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":307633,"subnation":{"id":56,"nameEn":"Washington","nameEs":"Washington","nameFr":"Washington","subnationCode":"WA","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":307633,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":297759,"subnation":{"id":58,"nameEn":"West Virginia","nameEs":"Virginia Occidental","nameFr":"Virginie-Occidentale","subnationCode":"WV","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":297759,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":405251,"subnation":{"id":35,"nameEn":"North Dakota","nameEs":"Dakota del Norte","nameFr":"Dakota du Nord","subnationCode":"ND","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":405251,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":313443,"subnation":{"id":10,"nameEn":"District of Columbia","nameEs":"Distrito de Columbia","nameFr":"District de Columbia","subnationCode":"DC","dnationId":225},"roundedSRank":"S3","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S3","speciesSubnational":{"elementSubnationalId":313443,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":365704,"subnation":{"id":20,"nameEn":"Indiana","nameEs":"Indiana","nameFr":"Indiana","subnationCode":"IN","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":365704,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":381625,"subnation":{"id":37,"nameEn":"New Hampshire","nameEs":"New Hampshire","nameFr":"New Hampshire","subnationCode":"NH","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":381625,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":264997,"subnation":{"id":33,"nameEn":"Montana","nameEs":"Montana","nameFr":"Montana","subnationCode":"MT","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":264997,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":332797,"subnation":{"id":55,"nameEn":"Vermont","nameEs":"Vermont","nameFr":"Vermont","subnationCode":"VT","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":332797,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":394635,"subnation":{"id":51,"nameEn":"Texas","nameEs":"Texas","nameFr":"Texas","subnationCode":"TX","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":394635,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":358508,"subnation":{"id":12,"nameEn":"Florida","nameEs":"Florida","nameFr":"Floride","subnationCode":"FL","dnationId":225},"roundedSRank":"SNR","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"SNR","speciesSubnational":{"elementSubnationalId":358508,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":294088,"subnation":{"id":30,"nameEn":"Missouri","nameEs":"Missouri","nameFr":"Missouri","subnationCode":"MO","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":294088,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":384334,"subnation":{"id":29,"nameEn":"Minnesota","nameEs":"Minnesota","nameFr":"Minnesota","subnationCode":"MN","dnationId":225},"roundedSRank":"SNR","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"SNR","speciesSubnational":{"elementSubnationalId":384334,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":278414,"subnation":{"id":52,"nameEn":"Utah","nameEs":"Utah","nameFr":"Utah","subnationCode":"UT","dnationId":225},"roundedSRank":"S4","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S4","speciesSubnational":{"elementSubnationalId":278414,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":355556,"subnation":{"id":48,"nameEn":"South Carolina","nameEs":"Carolina del Sur","nameFr":"Caroline du Sud","subnationCode":"SC","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":355556,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":384320,"subnation":{"id":36,"nameEn":"Nebraska","nameEs":"Nebraska","nameFr":"Nebraska","subnationCode":"NE","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":3,"dataSensitiveDescEn":"Conditional","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"C"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":384320,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":322722,"subnation":{"id":28,"nameEn":"Michigan","nameEs":"Michigan","nameFr":"Michigan","subnationCode":"MI","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":322722,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":283826,"subnation":{"id":9,"nameEn":"Connecticut","nameEs":"Connecticut","nameFr":"Connecticut","subnationCode":"CT","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":283826,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":293029,"subnation":{"id":34,"nameEn":"North Carolina","nameEs":"Carolina del Norte","nameFr":"Caroline du Nord","subnationCode":"NC","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":293029,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":362854,"subnation":{"id":32,"nameEn":"Mississippi","nameEs":"Mississippi","nameFr":"Mississippi","subnationCode":"MS","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":362854,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":336768,"subnation":{"id":88,"nameEn":"Navajo Nation","nameEs":"La Nación Navajo","nameFr":"Nation Navajo","subnationCode":"NN","dnationId":225},"roundedSRank":"S3","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S3","speciesSubnational":{"elementSubnationalId":336768,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":390119,"subnation":{"id":7,"nameEn":"California","nameEs":"California","nameFr":"Californie","subnationCode":"CA","dnationId":225},"roundedSRank":"SNR","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"SNR","speciesSubnational":{"elementSubnationalId":390119,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":339546,"subnation":{"id":41,"nameEn":"New York","nameEs":"Nueva York","nameFr":"New York","subnationCode":"NY","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":339546,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":402849,"subnation":{"id":1,"nameEn":"Alaska","nameEs":"Alaska","nameFr":"Alaska","subnationCode":"AK","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":402849,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":332853,"subnation":{"id":50,"nameEn":"Tennessee","nameEs":"Tennessee","nameFr":"Tennessee","subnationCode":"TN","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":332853,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":283968,"subnation":{"id":25,"nameEn":"Maryland","nameEs":"Maryland","nameFr":"Maryland","subnationCode":"MD","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":283968,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":270868,"subnation":{"id":44,"nameEn":"Oregon","nameEs":"Oregón","nameFr":"Oregon","subnationCode":"OR","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":270868,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":386780,"subnation":{"id":47,"nameEn":"Rhode Island","nameEs":"Rhode Island","nameFr":"Rhode Island","subnationCode":"RI","dnationId":225},"roundedSRank":"S3","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S3S4","speciesSubnational":{"elementSubnationalId":386780,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":388155,"subnation":{"id":43,"nameEn":"Oklahoma","nameEs":"Oklahoma","nameFr":"Oklahoma","subnationCode":"OK","dnationId":225},"roundedSRank":"SNR","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"SNR","speciesSubnational":{"elementSubnationalId":388155,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":319836,"subnation":{"id":24,"nameEn":"Massachusetts","nameEs":"Massachusetts","nameFr":"Massachusetts","subnationCode":"MA","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":319836,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":390092,"subnation":{"id":6,"nameEn":"Arizona","nameEs":"Arizona","nameFr":"Arizona","subnationCode":"AZ","dnationId":225},"roundedSRank":"S4","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S4","speciesSubnational":{"elementSubnationalId":390092,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":332176,"subnation":{"id":14,"nameEn":"Georgia","nameEs":"Georgia","nameFr":"Géorgie","subnationCode":"GA","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":332176,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":380159,"subnation":{"id":11,"nameEn":"Delaware","nameEs":"Delaware","nameFr":"Delaware","subnationCode":"DE","dnationId":225},"roundedSRank":"S3","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S3","speciesSubnational":{"elementSubnationalId":380159,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":399807,"subnation":{"id":42,"nameEn":"Ohio","nameEs":"Ohio","nameFr":"Ohio","subnationCode":"OH","dnationId":225},"roundedSRank":"SNR","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"SNR","speciesSubnational":{"elementSubnationalId":399807,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":304673,"subnation":{"id":53,"nameEn":"Virginia","nameEs":"Virginia","nameFr":"Virginie","subnationCode":"VA","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":304673,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":359755,"subnation":{"id":4,"nameEn":"Arkansas","nameEs":"Arkansas","nameFr":"Arkansas","subnationCode":"AR","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":359755,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":277226,"subnation":{"id":2,"nameEn":"Alabama","nameEs":"Alabama","nameFr":"Alabama","subnationCode":"AL","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":277226,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":270035,"subnation":{"id":23,"nameEn":"Louisiana","nameEs":"Louisiana","nameFr":"Louisiane","subnationCode":"LA","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":270035,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":384004,"subnation":{"id":49,"nameEn":"South Dakota","nameEs":"Dakota del Sur","nameFr":"Dakota du Sud","subnationCode":"SD","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":384004,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":293062,"subnation":{"id":18,"nameEn":"Idaho","nameEs":"Idaho","nameFr":"Idaho","subnationCode":"ID","dnationId":225},"roundedSRank":"S4","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S4","speciesSubnational":{"elementSubnationalId":293062,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":362855,"subnation":{"id":38,"nameEn":"New Jersey","nameEs":"Nueva Jersey","nameFr":"New Jersey","subnationCode":"NJ","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":362855,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":319851,"subnation":{"id":40,"nameEn":"Nevada","nameEs":"Nevada","nameFr":"Nevada","subnationCode":"NV","dnationId":225},"roundedSRank":"S4","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S4","speciesSubnational":{"elementSubnationalId":319851,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":268104,"subnation":{"id":26,"nameEn":"Maine","nameEs":"Maine","nameFr":"Maine","subnationCode":"ME","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":268104,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":375433,"subnation":{"id":59,"nameEn":"Wyoming","nameEs":"Wyoming","nameFr":"Wyoming","subnationCode":"WY","dnationId":225},"roundedSRank":"S4","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S4","speciesSubnational":{"elementSubnationalId":375433,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":365923,"subnation":{"id":19,"nameEn":"Illinois","nameEs":"Illinois","nameFr":"Illinois","subnationCode":"IL","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":365923,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":361261,"subnation":{"id":8,"nameEn":"Colorado","nameEs":"Colorado","nameFr":"Colorado","subnationCode":"CO","dnationId":225},"roundedSRank":"S4","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S4","speciesSubnational":{"elementSubnationalId":361261,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":396029,"subnation":{"id":17,"nameEn":"Iowa","nameEs":"Iowa","nameFr":"Iowa","subnationCode":"IA","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":396029,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":375749,"subnation":{"id":57,"nameEn":"Wisconsin","nameEs":"Wisconsin","nameFr":"Wisconsin","subnationCode":"WI","dnationId":225},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":375749,"hybrid":false,"exotic":false,"native":true}}],"nrankReviewYear":1996,"nrank":"N5","speciesNational":{"elementNationalId":167704,"exotic":false,"native":true}},{"elementNationalId":162893,"classifConfidence":null,"nation":{"id":38,"nameEn":"Canada","nameEs":"Canadá","nameFr":"Canada","isoCode":"CA","region":"Canada"},"roundedNRank":"N5","elementSubnationals":[{"elementSubnationalId":379963,"subnation":{"id":65,"nameEn":"Northwest Territories","nameEs":"Territorios del Noroeste","nameFr":"Territoires du Nord-Ouest","subnationCode":"NT","dnationId":38},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":379963,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":302715,"subnation":{"id":66,"nameEn":"Nova Scotia","nameEs":"Nueva Escocia","nameFr":"Nouvelle-Écosse","subnationCode":"NS","dnationId":38},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":302715,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":274908,"subnation":{"id":61,"nameEn":"British Columbia","nameEs":"Columbia Británica","nameFr":"Colombie-Britannique","subnationCode":"BC","dnationId":38},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":274908,"hybrid":false,"exotic":true,"native":true}},{"elementSubnationalId":355049,"subnation":{"id":91,"nameEn":"Labrador","nameEs":"Labrador","nameFr":"Labrador","subnationCode":"LB","dnationId":38},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":355049,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":404101,"subnation":{"id":69,"nameEn":"Quebec","nameEs":"Quebec","nameFr":"Québec","subnationCode":"QC","dnationId":38},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":404101,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":286559,"subnation":{"id":63,"nameEn":"New Brunswick","nameEs":"New Brunswick","nameFr":"Nouveau-Brunswick","subnationCode":"NB","dnationId":38},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":286559,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":296811,"subnation":{"id":62,"nameEn":"Manitoba","nameEs":"Manitoba","nameFr":"Manitoba","subnationCode":"MB","dnationId":38},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":296811,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":266345,"subnation":{"id":60,"nameEn":"Alberta","nameEs":"Alberta","nameFr":"Alberta","subnationCode":"AB","dnationId":38},"roundedSRank":"S5","dataSensitive":{"id":1,"dataSensitiveDescEn":"Yes","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"Y"},"dataSensitiveCategory":{"id":2,"dataSensitiveCategoryDescEn":"Proprietary Data","dataSensitiveCategoryDescEs":null,"dataSensitiveCategoryDescFr":null,"nsStandardInd":true},"srank":"S5","speciesSubnational":{"elementSubnationalId":266345,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":405416,"subnation":{"id":93,"nameEn":"Yukon Territory","nameEs":"Territorio del Yukón","nameFr":"Territoire du Yukon","subnationCode":"YT","dnationId":38},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":405416,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":297540,"subnation":{"id":92,"nameEn":"Island of Newfoundland","nameEs":"Isla de Terranova","nameFr":"Île de Terre­Neuve","subnationCode":"NF","dnationId":38},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":297540,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":316806,"subnation":{"id":227,"nameEn":"Nunavut","nameEs":"Nunavut","nameFr":"Nunavut","subnationCode":"NU","dnationId":38},"roundedSRank":"S3","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S3S4","speciesSubnational":{"elementSubnationalId":316806,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":394852,"subnation":{"id":68,"nameEn":"Prince Edward Island","nameEs":"Isla del Príncipe Eduardo","nameFr":"Île-du-Prince-Édouard","subnationCode":"PE","dnationId":38},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":394852,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":397996,"subnation":{"id":70,"nameEn":"Saskatchewan","nameEs":"Saskatchewan","nameFr":"Saskatchewan","subnationCode":"SK","dnationId":38},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":397996,"hybrid":false,"exotic":false,"native":true}},{"elementSubnationalId":394854,"subnation":{"id":67,"nameEn":"Ontario","nameEs":"Ontario","nameFr":"Ontario","subnationCode":"ON","dnationId":38},"roundedSRank":"S5","dataSensitive":{"id":2,"dataSensitiveDescEn":"No","dataSensitiveDescEs":null,"dataSensitiveDescFr":null,"dataSensitiveCode":"N"},"dataSensitiveCategory":null,"srank":"S5","speciesSubnational":{"elementSubnationalId":394854,"hybrid":false,"exotic":false,"native":true}}],"nrankReviewYear":2024,"nrank":"N5","speciesNational":{"elementNationalId":162893,"exotic":false,"native":true}}],"lastModified":"2026-10-02T21:34:55.607948Z","lastPublished":"2026-10-02T21:32:08.892226Z","promotionalDescription":null,"conceptLineageSummary":null,"nsxUrl":"/Taxon/ELEMENT_GLOBAL.2.100922/Castor_canadensis","grankAdjustmentReasons":null,"grankChangeDate":"1996-11-08","grankReviewDate":"2016-04-04","grankReasons":"Large range in North America; common; expanding populations.","grank":"G5","rankInfo":{"elementGlobalId":100922,"aooPercentGood":null,"enviromentalSpecificity":null,"intrinsicVulnerability":null,"longTermTrend":null,"numberEos":{"id":14,"numberEosDescEn":"81 to >300","numberEosDescEs":"De 81 a >300","numberEosDescFr":"De 81 à >300"},"numberGoodEos":null,"numberProtEos":{"id":14,"numberProtEosDescEn":"Many to very many (13 to >40) occurrences appropriately protected and managed","numberProtEosDescEs":"De varios a muchos casos (13 a >40) adecuadamente protegidos y controlados","numberProtEosDescFr":"De plusieurs à beaucoup d’occurrences (de 13 à >40) protégées et contrôlées convenablement"},"popSize":{"id":33,"popSizeDescEn":"10,000 to >1,000,000 individuals","popSizeDescEs":"De 10.000 a >1.000.000 de individuos","popSizeDescFr":"De 10 000 à >1 000 000 individus"},"rangeExtent":{"id":35,"rangeExtentDescEn":">2,500,000 square km (greater than 1,000,000 square miles)","rangeExtentDescEs":">2.500.000 kilómetros cuadrados (más ","rangeExtentDescFr":">2 500 000 km carrés (plus de 1 000 000 miles carrés)"},"shortTermTrend":{"id":44,"shortTermTrendDescEn":"Increase of >10%","shortTermTrendDescEs":"Aumento de >10%.","shortTermTrendDescFr":"Augmentation de >10 %"},"threatImpactAssigned":null,"rangeExtentComments":"North America except arctic tundra, peninsular Florida, and much of the desert area of the Southwest, including parts of the northern edge of Mexico; introduced into Eurasia.","areaOfOccupancy":null,"areaOfOccupancyComments":null,"numberEosComments":null,"popSizeComments":null,"viabilityComments":null,"threatImpactComments":"Other than intensive, unregulated trapping, or extensive removal of deciduous woody plants near permanent water sources (except in circumstances where old growth is replaced by young growth), there are few threats to beaver populations. In fact, once established in an area (e.g., a watershed or drainage system), beavers often are difficult to eliminate.","shortTermTrendComments":null,"longTermTrendComments":null,"inventoryNeeds":null,"numberProtEosComments":null,"protectionNeeds":"In situations where beaver protection is desired, it is necessary to protect both aquatic and riparian habitats. Generally beavers will modify the aquatic system to make it most suitable for themselves. Protection of an adequate amount of riparian habitat to meet the food and building needs of the beavers is critical; ideally the riparian habitat to be protected should extend at least 50 m from the water and should support young deciduous woody vegetation. Along streams, about 1 km of stream channel generally is sufficient to support one beaver family.","otherConsiderations":null,"intrinsicVulnerabilityComments":null,"enviromentalSpecificityComments":null},"animalCharacteristics":{"elementGlobalId":100922,"majorHabitat":{"id":3,"majorHabitatDescEn":"Terrestrial","majorHabitatDescEs":"Terrestre","majorHabitatDescFr":"Terrestre"},"nonMigrant":true,"localMigrant":false,"longDistanceMigrant":false,"mobilityMigrationComments":"Beavers usually stay within 0.8 km of the den (Schwartz and Schwartz 1981). The longest movements are made by dispersing two-year-olds (Hill 1982); these average 8-16 stream km but range up to 238 stream km (108 air km, Hibbard 1958). In Ohio, nearly all dispersers moved out of natal drainage system (Svendsen 1980). Families generally are at least 0.8-1.6 km apart (reviewed in Novak 1987a). In Manitoba, home range averaged 17.6 ha for solitary beavers and 7.7 ha for families (Wheatley 1997). <br><br>","foodHabitsComments":"The diet of the beaver changes throughout the year. Use of woody vegetation extends from fall to spring, peaking in winter and reaching a minimum in summer. Favored woody plants in many regions include aspen (POPULUS TREMULOIDES), willow (SALIX), cottonwood (POPULUS sp.), alder (ALNUS sp.), birch (BETULA), sweetgum (LIQUIDAMBAR STYRACIFLUA), blackgum (NYSSA), and pine (PINUS). Aspen is especially favored where it is available. Apparently alder often is cut for construction material and not for food, except when other sources are unavailable (see Novak 1987a). In general the beaver is flexible in its choice of woody plants and eats the leaves, bark, and twigs of most species. Beavers commonly debark pine trees and lick the pitch. <br><br>Summer foods include aquatic succulents such as pond lilies (NUPHAR, NYMPHAEA), bur-reed (SPARGANIUM), duckweeds (LEMNA, etc.), pondweeds (POTAMOGETON), algae, and fleshy rootstocks of many other species, as well as a wide variety of upland or riparian herbaceous plants. In addition, beavers in some areas commonly visit fields to eat and/or harvest clover, alfalfa, corn, soybeans, and other crops, some of which may be used as construction materials. Relatively little is known about the possible use of below-surface aquatic vegetation in winter. See Novak (1987a) for an overview of beaver food habits in different regions. <br><br>Naiman et al. (1988) cited various studies indicating that in northern regions beavers annually cut at least a metric ton of wood within approximately 100 m of their pond. In Wisconsin, it was estimated that a beaver family may cut about one-half acre (0.2 ha) per year in pole stands of 500 stems per acre (1250 stems per ha) (Knudsen 1962). Extensive tree cutting occurs only in late summer and fall (Adirondacks; Stegeman 1954). <br><br>In northern areas, beavers store food in late summer and fall for use in winter. Food cache construction begins at the end of August at the Mackenzie Delta (Aleksiuk 1970). Branches of woody plants are cached in deep pools near the den. Normally branches that are cut and carried to the cache are under 13 cm in diameter. The food pile may be capped with alder, peeled logs, or conifers. Caching provides an under-ice food supply in winter. In areas that rarely become heavily ice-covered, beavers do not always or regularly cache food (Swenson et al. 1983).","animalPhenologyComments":"Most beaver activity is crepuscular and nocturnal, but commonly they are active diurnally as well. According to Schwartz and Schwartz (1981) diurnal activity is most likely in fall. Beavers exhibit winter torpor but do not hibernate (Seal and Kreeger 1987). Rarely are beavers active above ice when temperatures are below -10 C.","colonialBreeder":false,"length":117,"width":null,"weight":27000,"animalPhenologies":[{"animalCagPhenologyId":101131,"animalPhenology":{"id":4,"animalPhenologyDescEn":"Nocturnal","animalPhenologyDescEs":"Nocturno","animalPhenologyDescFr":"Nocturne","displayOrder":4},"adult":true,"immature":true},{"animalCagPhenologyId":101132,"animalPhenology":{"id":5,"animalPhenologyDescEn":"Crepuscular","animalPhenologyDescEs":"Crepuscular","animalPhenologyDescFr":"Crépusculaire","displayOrder":5},"adult":true,"immature":true}],"animalFoodHabits":[{"animalCagFoodHabitsId":102189,"foodHabits":{"id":4,"foodHabitsDescEn":"Herbivore","foodHabitsDescEs":"Herbívoro","foodHabitsDescFr":"Herbivore","displayOrder":4},"adult":true,"immature":true}]},"occurrenceDelineations":[{"eoSpecsDetailId":1312,"locationUseClass":{"id":1,"locationUseClassDescEn":"Not applicable","locationUseClassDescEs":"No se aplica","locationUseClassDescFr":"Sans objet","displayOrder":1},"eoSpecGroupName":null,"subtypes":null,"inferredExtentDistance":1.8,"inferredExtentNotes":"Based on a home range of a colony of 125 hectares (see Separation Justification).","minimumEoCriteria":"Evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals in appropriate habitat where the species is presumed to be established and breeding.","mappingGuidance":null,"separationBarriers":"Impassable uplands (cliffs, etc.) that require more than 10 km route to circumvent.","separationDistanceUnsuitableHabitatat":5.0,"separationDistanceSuitableHabitatat":15.0,"altSeparationProcedure":null,"separationJustification":"Movements of dispersing two-year-olds may average 8-16 stream km but range up to 238 stream km (108 air km, Hibbard 1958, Hill 1982). In Ohio, nearly all dispersers moved out of their natal drainage system (Svendsen 1980). <br><br>Separation distances are arbitrary and not intended to delineate discrete populations. They attempt to balance extensive dispersal against the need for occurrences of practical size for conservation purposes.<br><br>Unsuitable habitat is defined as uplands away from water, or high gradient aquatic systems.","versionDate":"2004-09-22","versionAuthor":"Hammerson, G., and S. Cannings","versionNotes":null,"lastModified":"2020-02-25T18:14:06.836898Z"}],"plantCharacteristics":null,"elementManagement":{"elementGlobalId":100922,"eoManagementGroupName":null,"stewardshipOverview":null,"impacts":"Beavers may cause destruction through flooding of habitats of rare plants or animals (e.g., bog or fen species, Rawinski 1986, Rawinski and Lapin 1990; R. Radis, unpublished, who found that beaver flooding killed black spruce and other bog species along the Delaware and Kittatinny rivers).","restorationPotential":"Generally beavers easily can be reestablished in natural areas from which they have been extirpated. Simple protection from intensive trapping and, if necessary, translocation of animals trapped elsewhere are all that are needed if food supplies are adequate. Plans to reestablish beaver in an area should take into consideration the ecological and economic costs and benefits that may occur once the beavers begin building dams, cutting trees, and moving into adjacent available habitat as the population increases. <br><br>The recovery potential of sites damaged by flooding caused by beaver depends on the circumstances. In many instances (e.g., a flooded road or agricultural field) all that is needed is dewatering of the flooded area. However, little is known about the response and recovery potential of bogs and fens that have been flooded by beaver.","siteConservationPlansConsidered":null,"managementMethods":"Many areas inhabited by beaver, especially those also inhabited by humans, require active beaver management. The nature of the management depends on the particular conditions at the site and on the resource priorities established for the site (Allen 1987). In some situations beavers are desirable, whereas in other circumstances their presence may be detrimental to management goals. Often beavers present both positive and negative influences and a manager must weigh the benefits of beaver presence against the costs. The procedures discussed below cover most of the commonly encountered situations faced by those managing beavers. <br><br>The New York Department of Environmental Conservation (1991) pointed out that effective resolution of beaver-human conflicts is critical to maintaining public tolerance for beaver presence and that this tolerance is vital if the benefits of beaver presence are to be attained. <br><br>Protection of Individual Trees; Repellents <br><br>Individual trees can be protected by enclosing the bottom 1 m with heavy wire mesh, hardware cloth, or galvanized metal. The ends of the mesh should be wired together, rather than nailed to the tree. Leave enough space (about 15-30 cm) between the protective metal and the trunk to allow for tree growth; this also will prevent beavers from gnawing the bark through the mesh. Other coverings that sometimes have been successful include tar paper, Clark's tree wrap, and wood preservatives (e.g., Penta or creosote). <br><br>Commercial deer repellents (e.g., Thiram, Magic Circle, 10% solution of trinitrobenzene-aniline [TNB-A]) may deter beavers but may have an unpleasant odor (de Almeida 1987). The following results were reported in The American Tree Farmer (October 1983): full strength use of deer repellent (Magic Circle, $52 per 5 gallons in the late 1970s) was successful in repelling beavers every time. Beavers did not return when diluted repellent (1:50) was painted on the base of damaged trees along the shoreline. In a single pond in which the dam was blasted, a cord was run across the opening in the dam about 60 cm above the top of the remaining dam; rags were hung from the cord with the ends touching the dam and about 4 fluid ounces of repellent were poured on the rags; beavers did not return to the site for at least three years. In a 4-ha area occupied by beavers for 20 years, all dams were broken to a depth of 30 cm and rags were hung as described above; when diluted repellent was used, beavers rebuilt each dam within three months; with undiluted repellent, beavers did not return (frequency of reapplication was not stated). However, not all researchers have found deer repellents to be consistently effective when used as just described (Owen et al. 1984, cited by de Almeida 1987). <br><br>Another approach to protecting individual trees involves artificial feeding (leaving tree cuttings near beaver dens). This technique reduced damage to valued trees in Denver, Colorado, but obviously is not a long-term solution (Gray 1990). <br><br>Regulated Harvest Trapping and Nuisance Trapping <br><br>IMPORTANT NOTE: TRAPPING REGULATIONS VARY FROM STATE TO STATE; SOME OF THE PROCEDURES DISCUSSED IN THE FOLLOWING SECTIONS ARE ILLEGAL IN SOME STATES. <br><br>Beavers are most likely to become a management or stewardship problem when their population density is high. Regulated harvest during the furbearer trapping season is an obvious means of lowering population density and thus reducing the probability of a nuisance situation, while at the same time encouraging utilization of beaver as an economic resource. Moreover, this management approach can be employed at no cost to the landowner (trapper does the work for free in exchange for the benefits derived from the pelts obtained). <br><br>The level of harvest that is appropriate for a given area depends, of course, on management goals for that area. Annually removing about one-third of a beaver population (1.5-3 beaver per family, Ermer 1988) generally will prevent a population increase and will allow a sustained harvest (Hill 1982, Novak 1987a). <br><br>The traps usually used for beaver are no. 330 or 220 Conibear traps (kill traps), or no. 3 or no. 4 leghold traps (Hill 1982). Conibear traps are very effective and portable; time to death or unconsciousness is 1.5-9.25 minutes (Novak 1987b). Sets made with Conibear traps usually are easier to construct and can be used in a greater variety of situations than those made with leghold traps (Baker and Dwyer 1987); most professional trappers and fur trappers who are trapping principally for beaver use the no. 330 trap (Miller 1983). Two or three Conibear traps per family, set for about two weeks in winter during each of two years, effectively eliminated beaver in four Alabama watersheds (Hill 1976). Robertson (in Novak 1987b) captured 20 beavers per 100 trap nights using 330 Conibear traps in British Columbia. See Baker and Dwyer (1987) for further details on the use of Conibear traps for beaver. Novak (1987b) discusses the humane use of Conibear traps. He also describes some safety devices effective in preventing injury to the trapper. [Note: many states require first-time trappers to complete a trapper education course prior to obtaining a trapping permit. These courses demonstrate how to safely and effectively use traps.] <br><br>Leghold traps of size No. 3 or larger also are effective when properly used. To avoid escapes, these traps should be set to ensure drowning (Miller 1983). See Baker and Dwyer (1987) for further details on the use of leghold traps. These authors also describe the use of underice snare sets for capturing and killing beavers. In summary, underwater Conibear sets and drown sets employing leghold traps are recognized as legal, quick, and efficient methods for catching beavers (Tom Decker, Massachusetts Division of Fisheries and Wildlife, pers. comm.). <br><br>According to Hutchison et al. (1986), one professional trapper using water-based explosives and traps can wipe out an entire population by a single concentrated effort, with only occasional follow-up visits. These authors reported that professional trappers believe that the only way to protect timber from beaver is to remove beaver from the watershed; the trappers said that water control devices (see below) don't work, excluders (see below) are ineffective, and removing part of a population does not necessarily result in a lower water level. The trappers noted that a perpetual effort is needed to control a population if any beaver are allowed to remain in the watershed. <br><br>Miller (1983) stated that a week of trapping, especially if trapping is allowed in lodges and bank dens (prohibited by some states), usually is sufficient to remove all beavers from a single pond (cf. Novak [1987b], who reported that trappers rarely can catch all the beavers in a house). Miller noted that the removed beavers will be quickly replaced by others if beavers are common in surrounding areas. In Newfoundland, Bergerud and Miller (1977) found that one area from which beaver were removed was recolonized and occupied at former abundance levels within a few years. Miller described various effective trapping techniques and noted that it is not difficult for anyone with reasonable strength and some outdoor experience to become an effective beaver trapper. <br><br>Despite the difficulty that is sometimes encountered in totally removing beaver from an area, their confined ecological limits and low reproductive rate, together with the ease with which they may be trapped (usually), make beaver vulnerable to overharvest (Hill 1982). <br><br>Hutchison et al. (1986) pointed out a potential problem with removing beavers from an area--lowered water levels may expose the land to invasion by exotic plants. They did not provide any documentation for this point. <br><br>A final important note on kill trapping: beware of the possibility of capturing nontarget species--do not use exposed baits, which may attract raptors to sets (Bortolotti, cited in Novak 1987b); do not leave the remains of skinned animals near trap sets (may attract raptors or carnivores); properly adjust the pan tensioning devices on leghold traps (Novak 1987b). <br><br>Shooting <br><br>Hill (1982) stated that shooting can be effective in areas where boats and spotlights can be used (large rivers, lakes). According to Miller (1983), shooting rarely is effective for complete control and one's time would be better spent on trapping. <br><br>Poisoning <br><br>Hill (1976) found that strychnine alkaloid baits (sweetgum limbs painted with storax containing the poison) were consumed apparently without hesitation by both captive and wild beaver; most beavers died within 10 hours. He cautioned that additional work is needed to determine the hazards to other wildlife when the poison is used in this way. He also determined that the approximate minimal acute lethal dose of sodium monofluoroacetate (Compound 1080) was approximately 0.202 mg/kg. Hill warned that neither Compound 1080 nor strychnine are registered for use as a beaver control agent; their use for this purpose is illegal. Though initial research indicates that poisoning has some promise as a beaver control technique, political and practical considerations make it doubtful that this method ever will be an acceptable means of beaver control. <br><br>Live trapping <br><br>Sometimes a beaver problem can be alleviated by capturing and moving nuisance beavers to areas where their presence is not regarded as undesirable. It is a labor intensive, expensive method that generally is viable only when a dedicated group of volunteers is available to do the trapping and relocation. Usually Bailey or Hancock traps are used for live trapping beavers. The Hancock trap is preferable because of its greater catch efficiency and versatility (Novak 1987b). Apples and corn are effective baits (de Almeida 1987). Muller-Schwarze et al. (no date) noted that initial live trapping can be quite successful (one catch per 2-3 trap-nights). Later the beaver are more likely to avoid traps. <br><br>In some areas live trapping is not a feasible or allowable control method if the objective is to relocate the beavers. For example, the Connecticut Wildlife Bureau does not permit relocation of beavers because all suitable habitats are deemed to be saturated. As beaver populations and nuisance problems have increased, many states will not now accept beavers for relocation. Release of translocated beavers may not be appropriate in regions of high human density or where agriculture or road systems occupy low lying areas vulnerable to flooding. <br><br>Behavior and Maintenance of Live-trapped Beavers <br><br>Captured beavers can lacerate human skin with their claws and, as might be expected, can give a severe bite (Hill 1982). Some beavers may die of shock if restrained sufficiently long to attach ear tags (Hill 1982). Adults are too strong to handle without anaesthesia. Kits often can be handled without anaesthesia. <br><br>If beavers are to be penned for a few days prior to release, they should be kept wet and cool, and provided with water that they can enter for defecation (Novak 1987). Food (e.g. aspen twigs and leaves, apples) should <br><br>Novak (1987a) reviewed the literature on movements of transplanted beavers. The general pattern, based on several studies in various regions, is that a transplanted beaver may or may not move a great distance from the release site; many or most individuals can be expected to move at least a few miles, averaging perhaps 5-10 miles. <br><br>See Novak (1987) for a review of methods for tagging beavers. The most common method involves ear-tagging with No. 3 or No. 4 monel tags. Other methods employ colored or reflective markers, neck collars with lights, tattoos, tail notching, freeze-branding, fur bleaching, tetracycline, and radio collars (see Novak 1987a for references). <br><br>Immobilization <br><br>Seal and Kreeger (1987) recommended using ketamine (10 mg/kg) with acepromazine (0.2 mg/kg) in yearlings and adults; Lancia et al. (1978, in Hill 1982) reported that 10-13 mg/kg of ketamine hydrochloride plus 2.5 mg of acepromazine maleate was suitable for yearlings and adults. Ketamine alone is satisfactory for kits. The combination of ketamine and acepromazine produces sedation in 3-6 minutes with recovery in 1.5-7 hours. See Seal and Kreeger (1987) for additional information. <br><br>Biological Control There is no evidence that any nonhuman predator can be effective in controlling beaver populations. <br><br>Artificial Scent Mounds <br><br>Muller-Schwarze et al. (n.d.) found that artificial scent mounds were effective at deterring transient beaver from using existing but uninhabited lodges. Svendsen and Huntsman (1988) reported that scent mounds do not necessarily exclude nonresident beavers. <br><br>Chemosterilents <br><br>Chemosterilents have been field tested successfully on both males and females at Noxubee National Wildlife Refuge, Mississippi (Gordon and Arner 1976). The orally administered chemosterilents (17 alpha-ethynylestradiol-3-cyclopentyl ether and SC-24674 of Serle Laboratories; 1-2 mg/kg body weight, mixed with ethanol and placed in an apple), suppressed spermatogenesis and reduced ovulation and pregnancy. However effective application of this technique will have to await the development of efficient methods for treating wild beavers (Hill 1982). <br><br>Surgical Sterilization <br><br>Beavers should respond well to reproductive control because they are long-lived, apparently monogamous, and form discrete family units in which older progeny normally do not reproduce unless one or both parents are removed (Brooks et al. 1980; see also Muller-Schwarze et al., no date). Though surgical sterilization has limited application as a practical management tool, in. Denver, Colorado, where beavers are regarded as a nuisance along the Platte River Greenway and kill trapping is prohibited, the state wildlife commission funded a three-year control plan (in progress as of 1990) that involves surgical sterilization. Beavers are live-trapped by volunteers, sterilized by a volunteer veterinarian, who at the same time implants a radio transmitter. Radio-tagged beavers are being monitored by Division of Wildlife personnel. It is anticipated that the territorial behavior of the sterile animals will prevent nonsterile individuals from immigrating to the area and that population size will decrease due to lack of reproduction and immigration. <br><br>Exclusion Fencing <br><br>Fencing small critical areas such as culverts, drains, and small ponds or lakes sometimes can prevent damage, but often results in the beaver using the fence as construction material for a dam (Miller 1983). <br><br>Modification of Culverts and Beaver Dams <br><br>Important note: In some states, wetlands laws require that a permit be obtained before removing or destroying a beaver dam; this may entail a lengthy application and review process. <br><br>A common problem in beaver management is that of maintaining the water level lower than that sought by the beavers. Simply removing or breaching dams, or unplugging culverts, usually is ineffective because the beavers normally repair the damage within 24 hours. Daily destruction of dams or lodges sometimes may cause a family to relocate, but this is a labor intensive approach that is not practical in many situations. A better method of lowering the water level is to insert a drain pipe through the dam or culvert at the desired water level. In addition to decreasing the water level, an effective drain occasionally will cause the beavers to move to another site (Miller 1983). One method of drain installation, originally described by Carl Frentress, is included in Hammerson (1994) (note: most designs employ drain pipes of larger diameter than that described in this article). <br><br>Wire mesh cylinders (up to around four feet in diameter), rectangular home-made wooden pipes, and three-log drains have been used successfully to control water level in much the same way as described above. One successful design involves the use of a 4.5-m-long cylinder of concrete reinforcing mesh wrapped closely with one-inch by two-inch mesh fencing wire. This cylinder is sized to fit snugly inside a culvert (it also could be placed in a breach in a beaver dam). For most of its length, the protruding upstream end of the cylinder is surrounded by a larger-diameter cylinder of reinforcing mesh, with a six-inch space between the two-layered core cylinder and the outer mesh. Both ends of the core cylinder are capped with reinforcing mesh. The whole unit is held in place by metal fence posts driven into the pond bottom. <br><br>The three-log drain method (Arner 1963, Teaford 1986) is basically the same as the wire mesh cylinder method just described but substitutes for the wire mesh cylinder three green or waterlogged 10-16-foot logs (fastened together lengthwise, separated by spacers, and covered by roofing tin). Another technique substitutes for the wire mesh cylinder a rectangular wooden pipe that has the bottom side covered with wire mesh (Laramie 1963, Schemnitz 1980). See de Almeida (1987) and Schemnitz (1980:381) for some additional brief descriptions of drains that have been used to control water levels in beaver ponds. <br><br>Laramie (1963) noted that without monthly maintenance, about half the drain devices will fail. <br><br>Electrified Barriers <br><br>Electrified wires can be highly successful in controlling beaver flooding at sites where the activity of beavers is otherwise acceptable (Muller-Schwarze et al., n.d.). Such systems should be checked following heavy rains because rising water levels may short out the battery. The wires should be placed such that the beavers will not drag limbs behind the wire to plug a breached dam. Electrified systems work best in areas with little public exposure; otherwise vandalism probably will be a problem. Gaylord (no date) provided a description of a procedure for installing an electrified barrier. <br><br>Manipulation of the Food Supply <br><br>In the north and in the mountains, availability of a winter food supply is the most important factor affecting beaver distribution and abundance. Hence it is theoretically possible to affect beaver populations through manipulations of the vegetation. In general, activities that favor young woody deciduous growth will benefit the beaver. For example, clearing of tall hardwoods (for pine plantations) along streams along the Gulf Coast resulted in an abundance of beaver food (new growth) and nuisance complaints (Hill 1982). <br><br>According to Slough and Sadleir (1977), management of aspen, which depends primarily on fire to open up new areas for colonization, is a powerful tool in beaver management. They suggested that beaver populations (in the northern interior of British Columbia) would benefit from the protection of aspen from overuse by beaver by rotating the beaver harvest to allow aspen regeneration. In the Adirondacks of New York, Stegeman (1954) found that the size of aspen producing the greatest amount of beaver food per acre was the one-inch (2.5 cm) diameter class, which averaged 6.6 years of age. He suggested that the most advantageous rotation period for aspen for production of beaver food would be about 10 years. <br><br>Information gathered by Dieter and McCabe (1989) along a prairie river in South Dakota indicates that restricting grazing in the riparian zone would improve and expand beaver habitat. <br><br>Food supply manipulation is not an important management strategy in the south where food is not cached and where winter foods include many plant species (Hill 1982). Beier and Barrett (1987), who studied beaver habitat in the Sierra Nevada of California and Nevada, felt that the beaver's highly opportunistic food habits made it unlikely that beaver populations could be controlled through manipulation of forage resources. <br><br>Beaver, Cattle, and Stream Rehabilitation <br><br>Beavers have been used to help return to a predisturbance condition damaged streams in Wyoming and Oregon. In areas of southwestern Wyoming, overgrazing by cattle resulted in the loss of riparian vegetation, erosion, and lowering of the water table (Apple 1983, 1985). Initially an electrified fence was used to exclude livestock from a degraded stream course. This resulted in initial vegetative recovery and some bank stabilization. Then beavers were live-trapped and released in the enclosure (before complete willow recovery was attained). Several loads of aspen (stems 10-13 cm in diameter) were placed in the release sites coincident with the release of the beavers, which used the aspen to construct dams. The beaver dams changed a gully system into a pond system with adjacent meadows that benefited from the elevated water table. Willows recovered, with regrowth averaging 1.5 m tall at the end of the second year. In another degraded stream (unfenced) that beavers were attempting to colonize (but had failed to do so in the past due to their dams being too weak and washing out in spring), truck tires were wired together and placed across washed-out beaver dams. The beavers were able to build strong dams in these areas, impounding much more water than they could previously, and the dams withstood spring runoff. Mud bars and wetted sites above the dams provided excellent sites for vegetation reestablishment. The series of dams along the stream created conditions that prevented livestock from trailing up and down the stream, which aided in riparian recovery. The habitat changes induced by the beavers appeared to result in improved conditions for various wildlife species. <br><br>Munther (1981) stated that the immediate impact of cattle on a stream is often minor if beavers are established in wide valley willow habitats prior to the introduction of the cattle. Munther pointed out that in narrow valleys in western Montana, simultaneous feeding by beavers and cattle results in a gradual decline of willow and aspen due to removal of mature growth by beavers and harvest of new growth by cattle. Such a situation eventually may lead to the elimination of beaver, with subsequent further degradation of the vegetation by cattle as dams fail and the site becomes dewatered. The stream cuts a deeper channel, leaving the water table several feet lower than it was when the system was influenced by beavers. The end result is a system less suitable for both beavers and cattle. In western Montana, Munther felt that a year of rest from grazing was inadequate for rapid shrub recovery and that plantings (protected from livestock grazing) might be appropriate. He regarded the reestablishment of beaver and management for their continued presence as part of a well-conceived management strategy for grazed riparian ecosystems. Munther (1983) commented briefly on the incorporation of beavers into forest management in Lolo National Forest, Montana. <br><br>For information on the use of beaver to rehabilitate streams in Wyoming and Oregon, contact: Bruce Smith or Larry Apple, BLM, P.O. Box 1869, Rock Springs, WY 82901, and Jim R. Sedell, USFS, Forest Sciences Laboratory, Oregon State Univ., Corvallis, OR. Other contacts: Cliff Dahm, Oregon State Univ. Dept. of Fisheries and Wildlife; Greg Munther, U.S. Forest Service, Lolo National Forest, Missoula, MT 59801. <br><br>Managing Beaver Ponds for Waterfowl <br><br>Arner and Hepp (1989) discussed the importance and management of beaver ponds for waterfowl (especially mallard and wood duck) in the southeastern United States. Three situations were addressed: (1) ponds with shallow water and little emergent vegetation, (2) shallow ponds dominated by emergent vegetation, and (3) ponds with no possibilities for drainage. Recommended management techniques include installation of drains and planting of Japanese millet (in areas lacking suitable native vegetation, Teaford 1986) (situation 1); and maintaining or introducing favorable food and cover plants, and removing undesirable vegetation through burning, water-level manipulation, mechanical disturbance, and/or herbicides (situations 2 and 3). Arner and Hepp gave specific examples of favorable and unfavorable plants and provided some details on pond drains, burning, and herbicides.","monitoringMethods":"Monitoring methods depend on the size of the area to be monitored. Small nonremote areas can be covered readily on foot. Active family sites can be recognized readily in late fall by the presence of a food cache (except in the South) or by recent tree cutting, if the beavers themselves are not evident. Active beaver sites may be more difficult to locate in areas where bank dens are used, but cuttings usually help identify such sites. Payne (1982) placed aspen cuttings near the lodge entrance or inserted them through the lodge to check for beaver presence after trapping (the aspen will be eaten or gnawed if a beaver is present). <br><br>Aerial surveys are more efficient for larger areas that have difficult access. The efficiency of aerial surveys is affected by various factors, and sometimes results are poor (i.e. many beaver families are not detected) (Payne 1981), but a detection rate of 90% or more is possible (e.g. Swenson et al. 1983 [Montana prairie rivers], Bergerud and Miller 1977 [Newfoundland], Hay 1958 [Colorado Rockies]; see also Novak 1987a). Aerial surveys are not effective in areas where beavers do not construct conspicuous food caches. See Novak (1987a) for additional discussion and references on aerial surveys. <br><br>Ideally, population surveys should yield two kinds of information: the number of families and the number of individuals in each family. The number of families often is relatively easy to determine. In areas with extensive winter ice, this can be determined by counting the number of food caches (one cache per family) in the fall after leaves have fallen and before ice forms. In New York, active beaver colonies are identified (through aerial surveys) on the basis of a fresh winter food cache being present or, in the absence of a cache, by the presence of three of the following six indicators: muddy water in activity area, fresh cuttings in water or on bank, intact dam, fresh mud or sticks on dam or on bank, active trails on land, and freshly flooded or stressed trees or shrubs (New York Department of Environmental Conservation 1991). <br><br>Counts of the number of families may not reflect changes in population size because family size can change from year to year (Swenson et al. 1983). See Novak (1987a) for a discussion of methods for estimating beaver family size. <br><br>Annual harvest statistics, which may be available from the state wildlife division, are a useful supplement to population survey data. <br><br>Another technique used to examine beaver population trends in boreal environments involves the use of aerial photographs to detect habitat types that reflect new beaver activity or abandonment of a site (Broschart et al. 1989). According to Broschart et al., the method requires historical and recent aerial photos, experienced photo interpreters, and access to a GIS (geographic information system). Habitats identified in the photos are classified (e.g. per Cowardin et al. 1979) and the trends of the different types are determined. Broschart et al. (1989) examined the relationship of the habitat types to population levels as determined through fall aerial surveys and found that shallow marshes and seasonally flooded meadows were the two habitat types that provided the best estimate of beaver family density. Shallow marshes, which represent new flooding, were associated with an expanding beaver population; seasonally flooded meadows were associated with habitat abandonment as the beaver population decreased. Gross changes in beaver populations should be identifiable through the photographs even if different habitats are not easily distinguishable. The technique will not work where beaver live in bank dens, or where beaver do not develop food caches or create ponds (Broschart et al. 1989). Rebertus (1986) used aerial photographs effectively in documenting beaver use of bog habitats in northern Minnesota. <br><br>Remillard et al. (1987) used aerial photos to investigate plant community changes caused by beavers in the Adirondacks, New York. Kirby (1976) used aerial photography to map beaver flowages and associated wetlands in north-central Minnesota. Kirby concluded that the method was economical, adequately accurate, and substituted for detailed ground surveys, which were regarded as infeasible both economically and logistically. He agreed with previous investigators that familiarity with the vegetation is more important than is experience in photographic interpretation. Kirby's article includes several references on the use of aerial photography to map vegetation. Aerial photographs also have been used in New York to identify potential beaver sites and to determine occupancy levels (Dickinson 1971, Parsons and Brown 1978, Ermer 1980). See also Ermer (1980, cited in Gotie and Jenks 1984). <br><br>Gotie and Jenks (1984) found that interpretation of the New York State Freshwater Wetlands Inventory yielded a reasonable approximation of the number of potential beaver sites (compared to a direct interpretation of aerial photographs), especially in areas where beaver had been rare or absent for long periods. They found that it was more economical to work from the already completed wetlands inventory maps than from aerial photographs, though aerial photos were more effective in areas currently occupied by beavers. See New York Department of Environmental Conservation (1991) for further discussion of the population estimation methods used in New York. <br><br>Beier and Barrett (1987) developed stepwise logistic regression models that they felt could be used inexpensively in conjunction with maps and aerial photos to estimate the number of potential beaver colony sites along 1st- to 5th-order mountain streams in mixed-conifer habitats. Slough and Sadleir (1977) discussed the pitfalls of using remote sensing only to determine the land capability for beaver. <br><br>If intensive monitoring of a local protected population is planned, the beavers can be marked with monel ear tags to which a colored plastic swatch is attached (successfully used by Svendsen 1980). See Hill (1982) and Novak et al. (1987) for information on the use of radio telemetry equipment on beaver.","managementProgramContacts":"For information on water level control in beaver ponds, contact Carl Frentress, Wildlife Biologist, Texas Parks and Wildlife Department, Rt. 3, Box 3273, Athens, TX 74761; Neil Thurber, Beaver Stop Consulting, Inc., 3219 Coleman Road, NW, Calgary, Alberta, Canada T2L 1G6, phone (403) 282-6136; The Beaver Defenders, Unexpected Wildlife Refuge, P.O. Box 765, Newfield, NJ 08344; or Ron Gaines (Manager, Silver Creek Preserve, P.O. Box 624, Picabo, Idaho 83348; 208-788-2203). <br><br>[Users: please submit brief comments on management programs in your state, including the names and address of key personnel.]","monitoringProgramContacts":"Connecticut: Beeslick Pond, a groundwater-influenced wetland that rarely had been flooded; 15 rare plant species present.--In 1984 a culvert under the road crossing the outlet stream was plugged by beavers, resulting in at least a 20-cm increase in water level. The dam was removed in 1984, but plugged again between September, 1984, and May 1985, resulting in flooding through July, when the dam again was removed. No beaver activity was noted from July 1985 through 1987. By 1986 vegetation changes had occurred. Diversity of vascular plant species was reduced, 1984-1986. BETULA PUMILA and ACER RUBRUM appeared to be stressed. As of 1987, species richness and plant vigor aparoached pre-flood conditions. High water in 1986 in the absence of culvert plugging by the beaver may indicate that the road may be impounding water in the basin after heavy rains. Removal of beaver dams, and vegetation and water level monitoring are on-going. Goals are to avoid elimination of rare species, prevent damage to peat mats, and prevent invasion of exotics (e.g., purple loosestrife). See Rawinski and Lapin (1990). Key contacts: Tom Rawinski, Virginia Natural Heritage Program, 203 Governor St. Suite 402, Richmond, VA 23219, (804) 786-7951. <br><br>New York: White Lake Swamp, a marl fen bordering an outlet stream.--In the mid-1980s, beavers built a dam across the outlet, raising the water level in the lake, which in turn affected the vegetation surrounding the lake. ISOTRIA MEDEOLOIDES, once known to occur in the area, was flooded and has not been seen even after the lake water level returned to normal. <br><br>Key contact: Gerry Smith, The Nature Conservancy, Central/Western New York Chapters, Rochester, New York. <br><br>[Users: This section obviously is deficient; please submit information on monitoring programs in your state.]","managementResearchPrograms":"A study of the influence of beaver on the biogeochemistry of small streams and ponds in the Adirondacks is being conducted (1991) by Christopher P. Cirmo, Department of Civil Engineering, Syracuse University, 202 Hinds Hall, Syracuse, New York 13210, (315) 443-1245.","managementResearchNeeds":"Novak (1987) concluded that the following are important research needs: (1) quantification of when and how dispersing individuals die and how new colonies are established; (2) improved techniques for attaching radio transmitters; (3) development of a multiple-capture live trap, (a) for effective control of nuisance beavers, (b) to make trapping more economical for the trapper in the time it takes to catch a beaver, and (c) to enable the trapper to harvest selectively specific individuals from a group; (4) development of markets for the meat and other by-products of trapped beavers; (5) development of techniques to enable trappers to practice aspen regeneration around beaver ponds; and (6) development of techniques that can use the vast amount of data found at fur auction house. To these can be added several others, including the development of effective and efficient techniques for preventing flooding by beavers in areas where their eradication is not possible or desireable. Clearly research also is needed on the effect of the beaver on ecosystem structure and dynamics (e.g., in relation to rare wetland plants and animals).","biologicalResearchNeeds":null,"additionalTopics":"Those working with beavers should be aware that humans can contract tularemia by handling carcasses or wet skins of infected animals, by being bitten by a tick or deer fly that already has bitten an infected animal, or by consuming infected meat or water. Symptoms of tularemia include a small ulcer, sore, or black scab where the germ penetrated, enlarged underarm lymph nodes, fever, and other complications (see Addison et al. 1987 for further details). The disease responds to the various antibiotics. A basic precaution in handling a beaver carcass is to wear rubber gloves and disinfect any equipment that may have been in direct contact with a carcass. However, tularemia is not present in beaver populations in some areas of North America. <br><br>Beavers may transmit GIARDIA LAMBLIA, a pathogenic intestinal parasite that has caused human health problems in water supply systems (von Oettingen 1982). However, research by Woo and Paterson (1986) casts doubt on the role of beaver in contaminating water supplies with GIARDIA. Human cases of giardiasis seem to be caused primarily by drinking water from lakes and streams that have been contaminated with human feces (LaBastille 1986)."},"occurrenceViabilities":[{"eoRankSpecsDetailId":102482,"eoRankSpecsGroupName":null,"locationUseClass":{"id":1,"locationUseClassDescEn":"Not applicable","locationUseClassDescEs":"No se aplica","locationUseClassDescFr":"Sans objet","displayOrder":1},"excellentViability":null,"goodViability":null,"fairViability":null,"poorViability":null,"viabilityJustification":"Use the Generic Guidelines for the Application of Occurrence Ranks (2008).<br>The Key for Ranking Species Occurrences Using the Generic Approach provides a step-wise process for implementing this method.","versionDate":null,"versionAuthor":null,"versionNotes":null,"lastModified":"2020-05-14T02:17:37.79903Z"}],"references":[{"id":108482,"citation":"Addison, E. M., I. K. Barker, and D. B. Hunter. 1987. Diseases and parasites of furbearers. Pages 893-909 in M. Novak et al., editors. Wild furbearer management and conservation in North America. Ontario Ministry of Natural Resources.","shortCitationAuthor":"Addison et al.","shortCitationYear":1987,"referenceCode":"A87ADD01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":130924,"citation":"Aleksiuk, M. 1970. The seasonal food regime of arctic beavers. Ecology 51:264-270.","shortCitationAuthor":"Aleksiuk","shortCitationYear":1970,"referenceCode":"A70ALE01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":154110,"citation":"Allen, A. W. 1983. Habitat suitability index models: beaver. U.S. Fish and Wildlife Service, FWS/OBS-82/10.30, revised. 20 pp.","shortCitationAuthor":"Allen","shortCitationYear":1983,"referenceCode":"B83ALL02NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":381405,"citation":"Allen,  A. W. 1987. The relationship between habitat and furbearers. Pages 164-179 in M. Novak, J. A. Baker, M. E. Obbard, and B. Malloch, editors. Wild furbearer management and conservation in North America. Ontario Ministry of Natural Resources and the Ontario Trappers Association.","shortCitationAuthor":"Allen","shortCitationYear":1987,"referenceCode":"A87ALL05NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":1151804,"citation":"American Society of Mammalogists (ASM). 2025. Mammal Diversity Database (Version 1.13) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.10595931. Online. Available: https://www.mammaldiversity.org/","shortCitationAuthor":"American Society of Mammalogists (ASM)","shortCitationYear":2025,"referenceCode":"W25ASM01NAUS","lastModified":"2025-04-04T21:45:15.526109Z"},{"id":148736,"citation":"Anonymous. 1989. Improved drain for beaver ponds. The Habitat Express, U.S. Forest Service, Ogden, Utah.","shortCitationAuthor":"Anonymous","shortCitationYear":1989,"referenceCode":"U89ANO01NAUS","lastModified":"2020-02-25T18:14:06.836898Z"},{"id":136048,"citation":"Apple, L. L. 1983. The use of beavers in riparian/aquatic habitat restoration in a cold desert, gully-cut stream system: a case history. Proceeding of the 18th Annual Meeting Amercian Fisheries Society, Laramie, Wyoming, pages 29-35.","shortCitationAuthor":"Apple","shortCitationYear":1983,"referenceCode":"A83APP01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":136515,"citation":"Apple, L. L. 1985. Riparian habitat restoration and beaver. In: Riparian ecosystems and their management: reconciling conflicting uses. Rocky Mountain Forest and Range Experiment Station, USDA Forest Service, General Technical Report RM-120.","shortCitationAuthor":"Apple","shortCitationYear":1985,"referenceCode":"B85APP01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":153914,"citation":"Arner, D. H. 1963. Production of duck food in beaver ponds. Journal of Wildlife Management 27:76-81.","shortCitationAuthor":"Arner","shortCitationYear":1963,"referenceCode":"A63ARN01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":125370,"citation":"Arner, D. H., and G. R. Hepp. 1989. Beaver pond wetlands: a southern perspective. Pages 117-128 in L. M. Smith et al., editors. Habitat management for migrating waterfowl in North America. Texas Tech University Press, Lubbock. xii + 560 pp.","shortCitationAuthor":"Arner and Hepp","shortCitationYear":1989,"referenceCode":"A89ARN01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":136541,"citation":"Avery, E. L. 1983. A bibliography of beaver, trout, and wildlife, and forest relationships. Wisconsin Department of Natural Resources Technical Bulletin No. 137. 23 pp.","shortCitationAuthor":"Avery","shortCitationYear":1983,"referenceCode":"B83AVE01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":100513,"citation":"Baker, J. A., and P. M. Dwyer. 1987. Techniques and commercially harvesting furbearers. Pages 970-995 in M. Novak et al., editors. Wild furbearer management and conservation in North America. Ontario Ministry of Natural Resources.","shortCitationAuthor":"Baker and Dwyer","shortCitationYear":1987,"referenceCode":"A87BAK02NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":120395,"citation":"Baker, R. H. 1983. Michigan mammals. Michigan State University Press. 642 pp.","shortCitationAuthor":"Baker","shortCitationYear":1983,"referenceCode":"B83BAK01NAUS","lastModified":"2020-02-25T18:12:47.27318Z"},{"id":119122,"citation":"Banfield, A. W. F. 1974. The mammals of Canada. University of Toronto Press, Toronto, Canada. 438 pp.","shortCitationAuthor":"Banfield","shortCitationYear":1974,"referenceCode":"B74BAN01NAUS","lastModified":"2020-02-25T18:12:03.631914Z"},{"id":155533,"citation":"Bates, J. W. 1963. The effects of beaver on stream flow. Departmental Information Bulletin No. 63-13, Federal Aid Completion Report. Utah Sate Department of Fish and Game.","shortCitationAuthor":"Bates","shortCitationYear":1963,"referenceCode":"U63BAT01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":104672,"citation":"Beier, P., and R. H. Barrett. 1987. Beaver habitat use and impact in Truckee River basin, California. Journal of Wildlife Management 51:794-799.","shortCitationAuthor":"Beier and Barrett","shortCitationYear":1987,"referenceCode":"A87BEI01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":102777,"citation":"Bergerud, A. T., and D. R. Miller. 1977. Population dynamics of Newfoundland beaver. Canadian Journal of Zoology 55:1480-1492.","shortCitationAuthor":"Bergerud and Miller","shortCitationYear":1977,"referenceCode":"A77BER01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":149939,"citation":"Boyce, M. 1974. Beaver population ecology in interior Alaska. M.S. thesis, University of Alaska, Fairbanks. 161 pp.","shortCitationAuthor":"Boyce","shortCitationYear":1974,"referenceCode":"U74BOY01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":148358,"citation":"Bradt, G. W. 1938. A study of beaver colonies in Michigan. Journal of Mammalogy 19:139-62.","shortCitationAuthor":"Bradt","shortCitationYear":1938,"referenceCode":"A38BRA01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":136470,"citation":"Brenner, F. J. 1962. Food consumed by beavers in Crawford County, Pennsylvania. Journal of Wildlife Management 26:104-107.","shortCitationAuthor":"Brenner","shortCitationYear":1962,"referenceCode":"A62BRE01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":122345,"citation":"Brooks, R. P., M. W. Fleming, and J. J. Kennelly. 1980. Beaver colony response to fertility control: evaluating a concept. Journal of Wildlife Management 44:568-575.","shortCitationAuthor":"Brooks et al.","shortCitationYear":1980,"referenceCode":"A80BRO01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":116488,"citation":"Broschart, M. R., C. A. Johnston, and R. J. Naiman. 1989. Predicting beaver colony density in boreal landscapes. Journal of Wildlife Management 53:929-934.","shortCitationAuthor":"Broschart et al.","shortCitationYear":1989,"referenceCode":"A89BRO04NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":105253,"citation":"Buech, R. R. 1983. Modification of the Bailey live trap for beaver. Wildlife Society Bulletin 11:66-68.","shortCitationAuthor":"Buech","shortCitationYear":1983,"referenceCode":"A83BUE01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":102597,"citation":"Caire, W., J. D. Tyler, B. P. Glass, and M. A. Mares. 1989. Mammals of Oklahoma. University of Oklahoma Press, Norman. Oklahoma. 567 pp.","shortCitationAuthor":"Caire et al.","shortCitationYear":1989,"referenceCode":"B89CAI01NAUS","lastModified":"2020-02-25T18:12:05.975685Z"},{"id":148841,"citation":"Churchill, J. E. 1980. Beaver are killing our trout streams. Trout 21(4):22-25.","shortCitationAuthor":"Churchill","shortCitationYear":1980,"referenceCode":"A80CHU01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":143330,"citation":"Cliff, E. P. 1936. The beaver, empire builder and conservationist. Utah Juniper 7:23-26.","shortCitationAuthor":"Cliff","shortCitationYear":1936,"referenceCode":"A36CLI01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":146833,"citation":"Cowardin, L. M., et al. 1979. Classification of wetlands and deepwater habitats of the United States. U.S. Fish and Wildlife Service, FWS/OBS-79/31. 103 pp.","shortCitationAuthor":"Cowardin et al.","shortCitationYear":1979,"referenceCode":"B79COW01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":151169,"citation":"Crawford, H. S., R. G. Hooper, and R. F. Harlow. 1976. Woody plants selcted by beavers in the Appalachian Ridge and Valley Province. USDA Forest Service Research Paper NE-346.","shortCitationAuthor":"Crawford et al.","shortCitationYear":1976,"referenceCode":"B76CRA01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":117605,"citation":"de Almeida, M. H. 1987. Nuisance furbearer damage control in urban and suburban areas. Pages 996-1006 in M. Novak et al., editors. Wild furbearer management and conservation in North America. Ontario Ministry of Natural Resources.","shortCitationAuthor":"de Almeida","shortCitationYear":1987,"referenceCode":"A87DEM01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":126258,"citation":"Denney, R. N. 1952. A summary of North American beaver management, 1946-1948. Colorado Game and Fish Department, Curr. Rep. 28. 58 pp.","shortCitationAuthor":"Denney","shortCitationYear":1952,"referenceCode":"B52DEN01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":108130,"citation":"Dickinson, N. R. 1971. Aerial photographs as an aid in beaver management. New York Fish and Game Journal 18:57-61.","shortCitationAuthor":"Dickinson","shortCitationYear":1971,"referenceCode":"A71DIC01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":101537,"citation":"Dieter, C. D., and T. R. McCabe. 1989. Factors influencing beaver lodge-site selection on a prairie river. American Midland Naturalist 122:408-411.","shortCitationAuthor":"Dieter and McCabe","shortCitationYear":1989,"referenceCode":"A89DIE02NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":123024,"citation":"Dubec, L. J., R. B. Owen, and W. B. Krohn. 1988. Ecology of river otter on Mount Desert Island, Maine. Report to National Park Serice, North Atlantic Region, Boston, Massachusetts. 67 pp.","shortCitationAuthor":"Dubec et al.","shortCitationYear":1988,"referenceCode":"U88DUB01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":144496,"citation":"Dubec, L. J., W. B. Krohn, and R. B. Owen, Jr. 1990. Predicting occurrence of river otters by habitat on Mount Desert Island, Maine. J. Wildl. Manage. 54:594-599.","shortCitationAuthor":"Dubec et al.","shortCitationYear":1990,"referenceCode":"A90DUB01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":103092,"citation":"Easter-Pilcher, A. 1990. Cache size as an index to beaver colony size in northwestern Montana. Wildlife Society Bulletin 18:110-113.","shortCitationAuthor":"Easter-Pilcher","shortCitationYear":1990,"referenceCode":"A90EAS01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":997759,"citation":"Elliott, W. R. 2003. A guide to Missouri's cave life: 70 species brought to life. Missouri Department of Conservation. 37 pp.","shortCitationAuthor":"Elliott","shortCitationYear":2003,"referenceCode":"B03ELI01EHUS","lastModified":"2020-02-25T18:12:52.476544Z"},{"id":158432,"citation":"Emmons, L. H. and F. Feer. 1997. Neotropical rainforest mammals, a field guide. Second edition. Chicago, The University of Chicago Press.","shortCitationAuthor":"Emmons and Feer","shortCitationYear":1997,"referenceCode":"B97EMM0100LA","lastModified":"2020-02-25T18:12:58.226528Z"},{"id":104400,"citation":"Ermer, E. M. 1980. Beaver management studies in Region 9. New York Federal Aid in Fish and Wildlife Restoration Project W-139-D (annual report for Job 1-7). New York State Department of Environmental Conservation.","shortCitationAuthor":"Ermer","shortCitationYear":1980,"referenceCode":"U80ERM01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":156317,"citation":"Ermer, E. M. 1988. Managing beaver in New York. The Conservationist (State of New York, Department of Environmental Conservation), March-April, pp. 36-39.","shortCitationAuthor":"Ermer","shortCitationYear":1988,"referenceCode":"A88ERM01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":126765,"citation":"Ford, T. E., and R. J. Naiman. 1988. Alteration of carbon cycling by beaver: methane evasion rates from boreal forest streams and rivers. Canadian Journal of Zoology 66:529-533.","shortCitationAuthor":"Ford and Naiman","shortCitationYear":1988,"referenceCode":"A88FOR03NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":140747,"citation":"Francis, M. M., R. J. Naiman, and J. M. Melillo. 1985. Nitrogen fixation in subarctic streams influenced by beaver (<i>Castor canadensis</i>). Hydrobiologia 121:193-202.","shortCitationAuthor":"Francis et al.","shortCitationYear":1985,"referenceCode":"A85FRA04NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":106591,"citation":"Fuller, T. K., and J. A. Markl. 1987. Beaver, <i>Castor canadensis</i>, colony density in the Bearville Study Area, northcentral Minnesota. Canadian Field-Nat. 101:597-598.h","shortCitationAuthor":"Fuller and Markl","shortCitationYear":1987,"referenceCode":"A87FUL01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":120627,"citation":"Gard, R. 1961. Effects of beaver on trout in Sagehen Creek, California. Journal of Wildlife Management 25:221-242.","shortCitationAuthor":"Gard","shortCitationYear":1961,"referenceCode":"A61GAR01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":121224,"citation":"Gaylord, H. No date. A device for controlling water levels of beaver ponds. New York Department of Environmental Conservation. 2 pp., mimeo.","shortCitationAuthor":"Gaylord","shortCitationYear":null,"referenceCode":"UNDGAY01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":118294,"citation":"Godin, A. J. 1977. Wild mammals of New England. Johns Hopkins University Press, Baltimore. 304 pp.","shortCitationAuthor":"Godin","shortCitationYear":1977,"referenceCode":"B77GOD01NAUS","lastModified":"2020-02-25T18:12:30.710457Z"},{"id":148997,"citation":"Gordon, K. L., and D. H. Arner. 1976. Preliminary study using chemosterilants for control of nuisance beaver. Proceedings Annual Conference of Southeastern Association of Fish and Wildlife Agencies 30:464-465.","shortCitationAuthor":"Gordon and Arner","shortCitationYear":1976,"referenceCode":"A76GOR01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":112043,"citation":"Gotie, R. F., and D. L. Jenks. 1984. Assessment of the use of wetlands inventory maps for determining potential beaver habitat. New York Fish and Game Journal 31:55-62.","shortCitationAuthor":"Gotie and Jenks","shortCitationYear":1984,"referenceCode":"A84GOT01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":138935,"citation":"Grasse, J. E. 1951. Beaver ecology and management in the Rockies. Journal of Forestry 49(1):3-6.","shortCitationAuthor":"Grasse","shortCitationYear":1951,"referenceCode":"A51GRA01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":101880,"citation":"Grasse, J. E., and E. F. Putnam. 1950. Beaver management and ecology in Wyoming. Wyoming Game and Fish Commission, Bulletin 6. 52 pp.","shortCitationAuthor":"Grasse and Putnam","shortCitationYear":1950,"referenceCode":"B50GRA01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":124623,"citation":"Gray, M. T. 1990. Denver's urban beavers--a gnawing problem. Colorado Outdoors 39(1):27-29.","shortCitationAuthor":"Gray","shortCitationYear":1990,"referenceCode":"A90GRA03NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":132046,"citation":"Gunson, J. R. 1970. Dynamics of the beaver of Saskatchewan's northern forest. M.S. thesis, University of Alberta, Edmondton. 122 pp.","shortCitationAuthor":"Gunson","shortCitationYear":1970,"referenceCode":"U70GUN01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":153849,"citation":"Hakala, J. B. 1952. The life history and general ecology of the beaver (<i>Castor canadensis</i> Kuhl) in interior Alaska. M.S. thesis, University of Alaska, Fairbanks. 181 pp.","shortCitationAuthor":"Hakala","shortCitationYear":1952,"referenceCode":"U52HAK01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":119546,"citation":"Hall, E. R. 1981a. The Mammals of North America, second edition. Vols. I &amp; II. John Wiley &amp; Sons, New York, New York. 1181 pp.","shortCitationAuthor":"Hall","shortCitationYear":1981,"referenceCode":"B81HAL01NAUS","lastModified":"2020-02-25T14:38:13.267235Z"},{"id":125104,"citation":"Hamilton, W. J., Jr., and J. O. Whitaker, Jr. 1979. Mammals of the eastern United States. Cornell Univ. Press, Ithaca, New York. 346 pp.","shortCitationAuthor":"Hamilton and Whitaker","shortCitationYear":1979,"referenceCode":"B79HAM01NAUS","lastModified":"2020-02-25T18:12:03.881928Z"},{"id":152739,"citation":"Hammond, M. C. 1943. Beaver on the Lower Souris Refuge. Journal of Wildlife Management 7:316-321.","shortCitationAuthor":"Hammond","shortCitationYear":1943,"referenceCode":"A43HAM01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":115775,"citation":"Hand, D. 1984. The beaver's tale: out of the woods and into hot water. Smithsonian 15(8):162-170.","shortCitationAuthor":"Hand","shortCitationYear":1984,"referenceCode":"A84HAN02NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":131697,"citation":"Hay, K. G. 1958. Beaver census methods in the Rocky Mountain region. Journal of Wildlife Management 22:395-402.","shortCitationAuthor":"Hay","shortCitationYear":1958,"referenceCode":"A58HAY01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":810394,"citation":"Hebda, A.J. 2011. List of mammals of Nova Scotia (including synonyms used in the literature relating to Nova Scotia) (revision 2) 24 July 2011. Nova Scotia Museum Collections Unit, Halifax, Nova Scotia. 24 pp. Online. Available: https://naturalhistory.novascotia.ca/sites/default/files/inline/images/names_and_synonyms_ver3.pdf","shortCitationAuthor":"Hebda","shortCitationYear":2011,"referenceCode":"N11HEB01EHUS","lastModified":"2020-02-25T18:12:30.726311Z"},{"id":134578,"citation":"Heter, E. W. 1950. Transplanting beavers by airplane and parachute. Journal of Wildlife Management 14:143-147.","shortCitationAuthor":"Heter","shortCitationYear":1950,"referenceCode":"A50HET01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":143609,"citation":"Hibbard, E. A. 1958. Movements of beaver transplanted in North Dakota. Journal of Wildlife Management 22:209-211.","shortCitationAuthor":"Hibbard","shortCitationYear":1958,"referenceCode":"A58HIB01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":153363,"citation":"Hill, E. P. 1976. Control methods for nuisance beaver in the southeastern United States. Proceedings of the 7th Vertebrate Pest Conference, Monterey, California, pages 85-98.","shortCitationAuthor":"Hill","shortCitationYear":1976,"referenceCode":"A76HIL01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":139897,"citation":"Hill, E. P. 1982a. Beaver. Pages 256-281 in J. A. Chapman and G. A. Feldhamer, editors. Wild mammals of North America: biology, management, and economics. Johns Hopkins University Press, Baltimore. 1147 pp.","shortCitationAuthor":"Hill","shortCitationYear":1982,"referenceCode":"A82HIL01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":144525,"citation":"Hodgdon, H. E. 1978. Social dynamics and behavior within an unexploited beaver (<i>Castor canadensis</i>) population. Ph.D. dissertation, University of Massachusetts, Amherst. 292 pp.","shortCitationAuthor":"Hodgdon","shortCitationYear":1978,"referenceCode":"U78HOD01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":150505,"citation":"Hodgdon, H. E., and J. S. Larson. 1980. A bibliography of the recent literature on beaver. Massachusetts Agric. Exp. Sta. Res. Bull. 665. 128 pp.","shortCitationAuthor":"Hodgdon and Larson","shortCitationYear":1980,"referenceCode":"B80HOD01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":104882,"citation":"Hodkinson, I. D. 1975. Energy flow and organic matter decomposition in an abandoned beaver pond system. Oecologia 21:131-139.","shortCitationAuthor":"Hodkinson","shortCitationYear":1975,"referenceCode":"A75HOD01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":141017,"citation":"Hoover, R. L. 1955. Beaver ecology in the Longs Peak area of Colorado. M.S. thesis, Colorado A & M College, Fort Collins. 262 pp.","shortCitationAuthor":"Hoover","shortCitationYear":1955,"referenceCode":"U55HOO01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":144894,"citation":"Howard, R. J., and J. S. Larson. 1985. A stream habitat classification system for beaver. Journal of Wildlife Management 49:19-25.","shortCitationAuthor":"Howard and Larson","shortCitationYear":1985,"referenceCode":"A85HOW02NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":133702,"citation":"Hutchison, M. D., S. Olson, K. Lewis, and T. Vogt. 1986. Beaver at LaRue Swamp, Union County, Illinois: an assessment of their influences upon the area. Unpublished report. Natural Land Institute, Illinois 62908. 48 pp.","shortCitationAuthor":"Hutchison et al.","shortCitationYear":1986,"referenceCode":"U86HUT01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":116347,"citation":"Ives, R. L. 1942. The beaver-meadow complex. Journal of Geomorphology 5:191-203.","shortCitationAuthor":"Ives","shortCitationYear":1942,"referenceCode":"A42IVE01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":132728,"citation":"Jeglum, J. K. 1975. Vegetation-habitat changes caused by damming a peatland drainageway in northern Ontario. Canadian Field-Naturalist 89:400-412.","shortCitationAuthor":"Jeglum","shortCitationYear":1975,"referenceCode":"A75JEG01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":107435,"citation":"Jenkins, S. H. 1980. A size-distance relation in food selection by beavers. Ecology 61:740-746.","shortCitationAuthor":"Jenkins","shortCitationYear":1980,"referenceCode":"A80JEN02NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":153997,"citation":"Jenkins, S. H. and P. E. Busher. 1979. Castor canadensis. Am. Soc. Mamm., Mammalian Species No. 120:1-8.","shortCitationAuthor":"Jenkins and Busher","shortCitationYear":1979,"referenceCode":"A79JEN01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":115507,"citation":"Johnson, C. A., and R. J. Naiman. 1987. Boundary dynamics at the aquatic-terrestrial interface: the influence of beaver and geomorphology. Landscape Ecology 1(1):47-57.","shortCitationAuthor":"Johnson and Naiman","shortCitationYear":1987,"referenceCode":"A87JOH07NAUS","lastModified":"2020-02-25T18:14:06.836898Z"},{"id":125603,"citation":"Johnson, C. A., and R. J. Naiman. 1990. Aquatic patch creation in relation to beaver population trends. Ecology 71:1617-1621.","shortCitationAuthor":"Johnson and Naiman","shortCitationYear":1990,"referenceCode":"A90JOH08NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":137039,"citation":"Johnson, P. 1984. The dam builder is at it again! National Wildlife, June/July, pp. 9-15.","shortCitationAuthor":"Johnson","shortCitationYear":1984,"referenceCode":"A84JOH02NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":156383,"citation":"Jones, J. K., Jr., R. S. Hoffman, D. W. Rice, C. Jones, R. J. Baker, and M. D. Engstrom. 1992a. Revised checklist of North American mammals north of Mexico, 1991. Occasional Papers, The Museum, Texas Tech University, 146:1-23.","shortCitationAuthor":"Jones et al.","shortCitationYear":1992,"referenceCode":"B92JON01NAUS","lastModified":"2020-02-25T14:38:17.880059Z"},{"id":147007,"citation":"Kirby, R. E. 1976. Mapping wetlands on beaver flowages with 35-mm photography. Canadian Field-Naturalist 90:423-431.","shortCitationAuthor":"Kirby","shortCitationYear":1976,"referenceCode":"A76KIR01NAUS","lastModified":"2020-02-25T18:12:16.116448Z"},{"id":106533,"citation":"Knudsen, G. J. 1962. Relationship of beaver to forests, trout and wildlife in Wisconsin. Wisconsin Conservation Department Technical Wildlife Bulletin No. 25. 52 pp.","shortCitationAuthor":"Knudsen","shortCitationYear":1962,"referenceCode":"B62KNU01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":146464,"citation":"LaBastille, A. 1986. Beaver dammed again. Adirondack Life, March/April.","shortCitationAuthor":"LaBastille","shortCitationYear":1986,"referenceCode":"A86LAB01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":129426,"citation":"Lancia, R. A., R. P. Brooks, and M. W. Fleming. 1978. Ketamine hydrochloride as an immobilant and anesthetic for beaver. Journal of Wildlife Management 42:946-948.","shortCitationAuthor":"Lancia et al.","shortCitationYear":1978,"referenceCode":"A78LAN01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":107930,"citation":"Lang, G. E., and R. K. Wieder. 1984. The role of beaver in vegetation patterning and development in <i>Sphagnum</i>-dominated wetlands in West Virginia. Bulletin of the Ecological Society of America 65:243.","shortCitationAuthor":"Lang and Wieder","shortCitationYear":1984,"referenceCode":"A84LAN01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":154467,"citation":"Laramie, H. A., Jr. 1963. A device for control of problem beavers. Journal of Wildlife Management 27:471-476.","shortCitationAuthor":"Laramie","shortCitationYear":1963,"referenceCode":"A63LAR01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":141344,"citation":"Larson, J. S., and F. C. Van Nostrand. 1968. An evaluation of beaver aging techniques. Journal of Wildlife Management 32:99-103.","shortCitationAuthor":"Larson and Van Nostrand","shortCitationYear":1968,"referenceCode":"A68LAR01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":117673,"citation":"Larson, J. S., and S. J. Knapp. 1971. Sexual dimorphism in beaver neutrophils. Journal of Mammalogy 52:212-215.","shortCitationAuthor":"Larson and Knapp","shortCitationYear":1971,"referenceCode":"A71LAR01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":144120,"citation":"Leege, T. A. 1968. Natural movements of beavers in southeastern Idaho. Journal of Wildlife Management 32:973-976.","shortCitationAuthor":"Leege","shortCitationYear":1968,"referenceCode":"A68LEE01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":138042,"citation":"Libby, W. L. 1957. Observations on beaver movements in Alaska. Journal of Mammalogy 38:269.","shortCitationAuthor":"Libby","shortCitationYear":1957,"referenceCode":"A57LIB01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":810393,"citation":"Linzey, D.W. 2016. Mammals of Great Smoky Mountains National Park: 2016 revision. Southeastern Naturalist 15(Monograph 8):1–93.","shortCitationAuthor":"Linzey","shortCitationYear":2016,"referenceCode":"A16LIN02EHUS","lastModified":"2020-02-25T18:12:52.46115Z"},{"id":107316,"citation":"Lochmiller, R. L. 1979. Use of beaver ponds by southeastern woodpeckers in winter. Journal of Wildlife Management 43:263-266.","shortCitationAuthor":"Lochmiller","shortCitationYear":1979,"referenceCode":"A79LOC01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":141686,"citation":"MacArthur, R. A. 1989. Energy metabolism and thermoregulation of beaver (<i>Castor canadensis</i>). Canadian Journal of Zoology 67:651-657.","shortCitationAuthor":"MacArthur","shortCitationYear":1989,"referenceCode":"A89MAC02NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":141687,"citation":"MacArthur, R. A., and A. P. Dyck. 1990. Aquatic thermoregulation of captive and free-ranging beavers (<i>Castor canadensis</i>). Canadian Journal of Zoology 68:2409-2416.","shortCitationAuthor":"MacArthur and Dyck","shortCitationYear":1990,"referenceCode":"A90MAC02NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":158374,"citation":"Mammalian Species, nos. 1-604. Published by the American Society of Mammalogists.","shortCitationAuthor":"American Society of Mammalogists","shortCitationYear":null,"referenceCode":"JNDAME0100LA","lastModified":"2020-02-25T18:12:05.991304Z"},{"id":135601,"citation":"Maret, J. J., M. Parker, and T. E. Fanny. 1987. The effect of beaver ponds on the non-point source water quality of a stream in southwestern Wyoming. Water Resources 21(3):263-268.","shortCitationAuthor":"Maret et al.","shortCitationYear":1987,"referenceCode":"A87MAR03NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":148280,"citation":"McComb, W. C., J. R. Sedell, and T. D. Buchholz. 1990. Dam-site selection by beavers in an eastern Oregon basin. Great Basin Naturalist 50:273-281.","shortCitationAuthor":"McComb et al.","shortCitationYear":1990,"referenceCode":"A90MCC06NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":136226,"citation":"McGinley, M. A., and T. G. Whitham. 1985. Central place foraging by beavers (<i>Castor canadensis</i>): a test of foraging predictions and the impact of selective feeding on the growth form of cottonwoods (<i>Populus fremontii</i>). Oecologia 66:558-562.","shortCitationAuthor":"McGinley and Whitham","shortCitationYear":1985,"referenceCode":"A85MCG02NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":103549,"citation":"Medin, D. E. 1988. Beaver in western North America: an annotated bibliography, 1966-1086. USDA Forest Service, General Technical Report INT-242. [microfiche A13.88:INT-242]","shortCitationAuthor":"Medin","shortCitationYear":1988,"referenceCode":"B88MED01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":155371,"citation":"Michelmore, P. 1984. The amazing beavers of Currant Creek. Reader's Digest 124(744):109-113.","shortCitationAuthor":"Michelmore","shortCitationYear":1984,"referenceCode":"A84MIC01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":151171,"citation":"Miller, J. E. 1983. Beavers. Prevention and control of wildlife damage. Cooperative Extension Service, Institute of Agricultural and Natural Resources, University of Nebraska, Lincoln.","shortCitationAuthor":"Miller","shortCitationYear":1983,"referenceCode":"B83MIL01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":156110,"citation":"Morgan, L. H. 1868. The American beaver. Dover Publications, Inc. 384 pp.","shortCitationAuthor":"Morgan","shortCitationYear":1868,"referenceCode":"B68MOR01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":386793,"citation":"Müller-Schwarze, D., and L. Sun. 2003. The beaver: natural history of a wetlands engineer. Cornell University Press, Ithaca, New York. 190 pp.","shortCitationAuthor":"Muller-Schwarze and Sun","shortCitationYear":2003,"referenceCode":"B03MUL01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":144422,"citation":"Muller-Schwarze, D., et al. No date. On a study of the behavioral and population ecology of the beaver at Acadia National Park. National Park Service Cooperative Research Unit, State University of New York, College of Environmental Science and Forestry, Institute of Environmental Program Affairs, Syracuse, New York. 86 pp.","shortCitationAuthor":"Muller-Schwarze et al.","shortCitationYear":null,"referenceCode":"UNDMUL01NAUS","lastModified":"2020-02-25T18:14:06.836898Z"},{"id":118277,"citation":"Munther, G. L. 1981. Beaver management in grazed riparian ecosystems. Proceedings of the Wildlife-Livestock Relationships Symposium, Coeur d'Alene, Idaho, pages 234-241.","shortCitationAuthor":"Munther","shortCitationYear":1981,"referenceCode":"A81MUN01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":130728,"citation":"Munther, G. L. 1983. Integration of beaver into forest management. Proceedings of the 18th Annual Meeting of the American Fisheries Society (Laramie, Wyoming), pages 73-80.","shortCitationAuthor":"Munther","shortCitationYear":1983,"referenceCode":"A83MUN01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":119268,"citation":"Naiman, R. J., and J. M. Melillo. 1984. Nitrogen budget of a subarctic stream altered by beaver (<i>Castor canadensis</i>). Oecologia 62:150-155.","shortCitationAuthor":"Naiman and Melillo","shortCitationYear":1984,"referenceCode":"A84NAI02NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":110430,"citation":"Naiman, R. J., C. A. Johnston, and J. C. Kelley. 1988. Alteration of North American streams by beaver. BioScience 38:753-762.","shortCitationAuthor":"Naiman et al.","shortCitationYear":1988,"referenceCode":"A88NAI01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":137816,"citation":"Naiman, R. J., D. M. McDowell, and B. S. Farr. 1984. The influence of beaver (<i>Castor canadensis</i>) on the production dynamics of aquatic insects. Vehr. Internat. Verein. Limnol. 22:1801-1810.","shortCitationAuthor":"Naiman et al.","shortCitationYear":1984,"referenceCode":"A84NAI01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":104248,"citation":"Naiman, R. J., J. M. Melillo, and J. E. Hobbie. 1986. Ecosystem alteration of boreal forest streams by beaver (<i>Castor canadensis</i>). Ecology 67:1254-1269.","shortCitationAuthor":"Naiman et al.","shortCitationYear":1986,"referenceCode":"A86NAI01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":109264,"citation":"Neff, D. J. 1957. Ecological effects of beaver habitat abandonment in the Colorado Rockies. Journal of Wildlife Management 21:80-84.","shortCitationAuthor":"Neff","shortCitationYear":1957,"referenceCode":"A57NEF01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":116409,"citation":"Neff, D. J. 1959. A seventy-year history of a Colorado beaver colony. Journal of Mammalogy 40:381-387.","shortCitationAuthor":"Neff","shortCitationYear":1959,"referenceCode":"A59NEF01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":139736,"citation":"New York Department of Environmental Conservation. 1991. Status of beaver management in New York. Draft report.","shortCitationAuthor":"New York Department of Environmental Conservation","shortCitationYear":1991,"referenceCode":"U91NEW01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":139933,"citation":"Northcott, T. H. A. 1964. An investigation of the factors affecting carrying capacity of selected areas in Newfoundland for the beaver, <i>Castor canadensis caecator</i> Bangs, 1913. M.S. thesis, Memorial University, St. John's, Newfoundland. 133 pp.","shortCitationAuthor":"Northcott","shortCitationYear":1964,"referenceCode":"U64NOR01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":104154,"citation":"Novak, M. 1977. Determining the average size and composition of beaver families. Journal of Wildlife Management 41:751-754.","shortCitationAuthor":"Novak","shortCitationYear":1977,"referenceCode":"A77NOV01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":134711,"citation":"Novak, M. 1987a. Beaver. Pages 283-313 in M. Novak, et al. editors. Wild furbearer management and conservation in North America. Ontario Ministry of Natural Resources.","shortCitationAuthor":"Novak","shortCitationYear":1987,"referenceCode":"A87NOV01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":110477,"citation":"Novak, M. 1987b. Traps and trap research. Pages 941-969 in M. Novak et al., editors. Wild furbearer management and conservation in North America. Ontario Ministry of Natural Resources.","shortCitationAuthor":"Novak","shortCitationYear":1987,"referenceCode":"A87NOV02NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":132221,"citation":"Novak, M., et al., editors. 1987. Wild furbearer management and conservation in North America. Ontario Ministry of Natural Resources. 1150 pp.","shortCitationAuthor":"Novak et al.","shortCitationYear":1987,"referenceCode":"B87NOV01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":138099,"citation":"Novakowski, N. S. 1965. Population dynamics of a beaver population in northern latitudes. Ph.D. dissertation, University of Saskatchewan, Saskatoon. 154 pp.","shortCitationAuthor":"Novakowski","shortCitationYear":1965,"referenceCode":"U65NOV01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":104862,"citation":"Nowak, R. M. 1991. Walker's mammals of the world. Fifth edition. Vols. I and II. Johns Hopkins Univ. Press, Baltimore. 1629 pp.","shortCitationAuthor":"Nowak","shortCitationYear":1991,"referenceCode":"B91NOW01NAUS","lastModified":"2020-02-25T18:12:03.881928Z"},{"id":119364,"citation":"Obbard, M. E., et al. 1987. Furbearer harvests in North America. Pages 1007-1034 in M. Novak et al., eds. Wild furbearer management and conservation in North America. Ontario Ministry of Natural Resources and The Ontario Trappers Association. 1150 pp.","shortCitationAuthor":"Obbard et al.","shortCitationYear":1987,"referenceCode":"A87OBB01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":140230,"citation":"Parker, M. 1986. Beaver, water quality, and riparian systems. Pages 88-94 in Proceedings: Wyoming water and streamside zone conference. Wyoming Water Research Center, University of Wyoming, Laramie.","shortCitationAuthor":"Parker","shortCitationYear":1986,"referenceCode":"A86PAR02NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":136649,"citation":"Parsons, G. R., and M. K. Brown. 1978. An assessment of aerial photograph interpretation for recognizing potential beaver colony sites. New York Fish and Game Journal 25:175-177.","shortCitationAuthor":"Parsons and Brown","shortCitationYear":1978,"referenceCode":"A78PAR01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":133636,"citation":"Payne, N. F. 1981. Accuracy of aerial censusing for beaver colonies in Newfoundland. Journal of Wildlife Management 45:1014-1016.","shortCitationAuthor":"Payne","shortCitationYear":1981,"referenceCode":"A81PAY01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":128088,"citation":"Payne, N. F. 1982. Colony size, age, and sex structure of Newfoundland beaver. Journal of Wildlife Management 46:655-661.","shortCitationAuthor":"Payne","shortCitationYear":1982,"referenceCode":"A82PAY01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":138966,"citation":"Rawinski, T. J., and B. P. Lapin. 1990. Some effects of beaver flooding on rare swamp birch (<i>Betula pumila</i> L.) vegetation in Connecticut: 1984-1987. Pages 244-247 in: Ecosystem management: are species and significant habitats. New York State Museum Bulletin 471.","shortCitationAuthor":"Rawinski and Lapin","shortCitationYear":1990,"referenceCode":"A90RAW01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":151214,"citation":"Rebertus, A. J. 1986. Bogs as beaver habitat in north-central Minnesota. American Midland Naturalist 116:240-245.","shortCitationAuthor":"Rebertus","shortCitationYear":1986,"referenceCode":"A86REB01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":115089,"citation":"Reese, K. P. , and J. D. Hair. 1976. Avian species diversity in relation to beaver pond habitats in the Piedmont region of South Carolina. Proc. Annual Conf. Southeast. Fish and Wildl. Agencies 30:437-447.","shortCitationAuthor":"Reese and Hair","shortCitationYear":1976,"referenceCode":"A76REE01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":108261,"citation":"Reid, K. A. 1952. Effects of beavers on trout waters. Maryland Conserv. 29(4):21-23.","shortCitationAuthor":"Reid","shortCitationYear":1952,"referenceCode":"A52REI01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":107100,"citation":"Remillard, M. M., G. K. Gruendling, and D. J. Bogucki. 1987. Disturbance by beaver (<i>Castor canadensis</i> Kuhl) and increased landscape heterogeneity. Pages 103-122 in M. G. Turner, editor. Ecological Studies 64. Landscape heterogeneity and disturbance. Springer-Verlag, New York.","shortCitationAuthor":"Remillard et al.","shortCitationYear":1987,"referenceCode":"A87REM01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":108388,"citation":"Reynolds, R. E., and J. C. Lewis. 1976. Evaluating beaver guards on restricted flow risers of flood control impoundments. Ann. Conf. Southeast. Assoc. Fish and Game Comm. 13:455-462.","shortCitationAuthor":"Reynolds and Lewis","shortCitationYear":1976,"referenceCode":"A76REY01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":124390,"citation":"Rutherford, W. H. 1955. Wildlife and environmental relationships of beavers in Colorado forests. Journal of Forestry 53(11):803-806.","shortCitationAuthor":"Rutherford","shortCitationYear":1955,"referenceCode":"A55RUT01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":113734,"citation":"Ryden, H. 1988. The beaver is one smart rat. Audubon, September, pages 96-105.","shortCitationAuthor":"Ryden","shortCitationYear":1988,"referenceCode":"A88RYD01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":112246,"citation":"Schemnitz, S. D. 1980. Wildlife management techniques manual. 4th edition. The Wildlife Society, Washington, D.C. 686 pp.","shortCitationAuthor":"Schemnitz","shortCitationYear":1980,"referenceCode":"B80SCH01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":100987,"citation":"Schwartz, C. W., and E. R. Schwartz. 1981. The wild mammals of Missouri. University of Missouri Press, Columbia. 356 pp.","shortCitationAuthor":"Schwartz and Schwartz","shortCitationYear":1981,"referenceCode":"B81SCH01NAUS","lastModified":"2020-02-25T18:12:47.27318Z"},{"id":154561,"citation":"Seal, U. S., and T. J. Kreeger. 1987. Chemical immobilization of furbearers. Pages 191-215 in M. Novak et al., editors. Wild furbearer management and conservation in North America. Ontario Ministry of Natural Resources.","shortCitationAuthor":"Seal and Kreeger","shortCitationYear":1987,"referenceCode":"A87SEA01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":118626,"citation":"Shelton, P. C., and R. O. Peterson. 1983. Beaver, wolf and moose interactions in Isle Royale National Park, U.S.A. Acta Zool. Fenn. 174:265-266.","shortCitationAuthor":"Shelton and Peterson","shortCitationYear":1983,"referenceCode":"A83SHE01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"},{"id":128210,"citation":"Slough, B. G., and R. M. F. S. Sadleir. 1977. A land capability classification system for beaver (<i>Castor canadensis</i>). Canadian Journal of Zoology 55:1324-1335.","shortCitationAuthor":"Slough and Sadleir","shortCitationYear":1977,"referenceCode":"A77SLO01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":111908,"citation":"Smith, M. E., et al. 1991. Modification of stream ecosystem structure and function by beaver (<i>Castor canadensis</i>) in the Adirondack Mountains, New York. Canadian Journal of Zoology 69:55-61.","shortCitationAuthor":"Smith et al.","shortCitationYear":1991,"referenceCode":"A91SMI04NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":109332,"citation":"Stegeman, L. C. 1954. The production of aspen and its utilization on the Huntington Forest. Journal of Wildlife Management 18:348-358.","shortCitationAuthor":"Stegeman","shortCitationYear":1954,"referenceCode":"A54STE02NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":150005,"citation":"Svendsen, G. E. 1980. Population parameters and colony composition of beaver (Castor canadensis) in southeast Ohio. American Midland Naturalist 104:47-56.","shortCitationAuthor":"Svendsen","shortCitationYear":1980,"referenceCode":"A80SVE01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":144724,"citation":"Svendsen, G. E. 1989. Pair formation, duration of pair-bonds, and mate replacement in a population of beavers (<i>Castor canadensis</i>). Canadian Journal of Zoology 67:336-340.","shortCitationAuthor":"Svendsen","shortCitationYear":1989,"referenceCode":"A89SVE01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":150991,"citation":"Svendsen, G. E., and W. D. Huntsman. 1988. A field bioassay of beaver castoreum and some of its components. American Midland Naturalist 120:144-149.","shortCitationAuthor":"Svendsen and Huntsman","shortCitationYear":1988,"referenceCode":"A88SVE01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":150433,"citation":"Swank, W. E. 1949. Beaver ecology and management in West Virginia. Conserv. Comp. WV. 65pp.","shortCitationAuthor":"Swank","shortCitationYear":1949,"referenceCode":"B49SWA01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":135476,"citation":"Swenson, J. E., S. J. Knapp, P. R. Martin, and T. C. Hinz. 1983. Reliability of aerial cache surveys to monitor beaver population trends on prairie rivers in Montana. Journal of Wildlife Management 47:697-703.","shortCitationAuthor":"Swenson et al.","shortCitationYear":1983,"referenceCode":"A83SWE01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":128738,"citation":"Taylor, D. 1970. Growth, decline, and equilibrium in a beaver population at Sagehen Creek, California. Ph.D. dissertation, University of California, Berkeley.","shortCitationAuthor":"Taylor","shortCitationYear":1970,"referenceCode":"U70TAY01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":122080,"citation":"Teaford, J. W. 1986c. Beaver pond management. Section 5.5.2, U.S. Army Corps of Engineers Wildlife Resources Manual, Technical Report EL-86-10, Waterways Experiment Station, P.O. Box 631, Vickburg, Mississippi 39180-0631.","shortCitationAuthor":"Teaford","shortCitationYear":1986,"referenceCode":"A86TEA01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":109682,"citation":"Van Nostrand, F. C., and A. B. Stephenson. 1964. Age determination for beavers by tooth development. Journal of Wildlife Management 28:430-434.","shortCitationAuthor":"Van Nostrand and Stephenson","shortCitationYear":1964,"referenceCode":"A64VAN01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":130773,"citation":"Voigt, D. R., G. B. Kolenosky, and D. H. Pimlott. 1976. Changes in summer foods of wolves in central Ontario. Journal of Wildlife Management 49:663-668.","shortCitationAuthor":"Voigt et al.","shortCitationYear":1976,"referenceCode":"A76VOI01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":107253,"citation":"von Dettingen, S. L. 1982. A survey of beaver in central Massachusetts for <i>Giardia lamblia</i>. M.S. thesis, University of Massachusetts, Amherst. 58 pp.","shortCitationAuthor":"von Dettingen","shortCitationYear":1982,"referenceCode":"U82VON01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":149323,"citation":"Wallace, J. B., and A. C. Behnke. 1984. Quantification of wood habitat in subtropical Coastal Plain streams. Canadian Journal of Fisheries and Aquatic Sci. 41:1643-1652.","shortCitationAuthor":"Wallace and Behnke","shortCitationYear":1984,"referenceCode":"A84WAL03NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":154976,"citation":"Wheatley, M. 1997. Beaver, <i>Castor canadensis</i>, home range size and patterns of use if the taiga of southeastern Manitoba. Canadian Field-Naturalist 111:204-222. [three separate papers, parts I, II, and III, combined here]","shortCitationAuthor":"Wheatley","shortCitationYear":1997,"referenceCode":"A97WHE01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":107638,"citation":"Wigley, T. B., T. H. Roberts, and D. H. Arner. 1983. Reproductive characteristics of beaver in Mississippi. Journal of Wildlife Management 47:1172-1177.","shortCitationAuthor":"Wigley et al.","shortCitationYear":1983,"referenceCode":"A83WIG01NAUS","lastModified":"2020-02-25T18:14:06.899368Z"},{"id":122655,"citation":"Wilde, S. A., C. T. Youngberg, and H. H. Hovind. 1950. Changes in composition of ground water, soil fertility, and forest growth produced by the construction and removal of beaver dams. Journal of Wildlife Management 14:123-128.","shortCitationAuthor":"Wilde et al.","shortCitationYear":1950,"referenceCode":"A50WIL01NAUS","lastModified":"2020-02-25T18:14:06.883737Z"},{"id":117022,"citation":"Wilson, D. E., and D. M. Reeder (editors). 1993. Mammal species of the world: a taxonomic and geographic reference. Second edition. Smithsonian Institution Press, Washington, DC. xviii + 1206 pp. Available online at: http://www.nmnh.si.edu/msw/.","shortCitationAuthor":"Wilson and Reeder","shortCitationYear":1993,"referenceCode":"B93WIL01NAUS","lastModified":"2020-02-25T14:38:17.880059Z"},{"id":477777,"citation":"Wilson, D. E., and D. M. Reeder (editors). 2005. Mammal species of the world: a taxonomic and geographic reference. Third edition. The Johns Hopkins University Press, Baltimore. Two volumes. 2,142 pp. [As modified by ASM the Mammal Diversity Database (MDD) at https://www.mammaldiversity.org/index.html]","shortCitationAuthor":"Wilson and Reeder","shortCitationYear":2005,"referenceCode":"B05WIL01NAUS","lastModified":"2022-07-02T00:44:59.638537Z"},{"id":138611,"citation":"Wilson, D. E., and S. Ruff. 1999. The Smithsonian book of North American mammals. Smithsonian Institution Press, Washington, D.C. 750 pp.","shortCitationAuthor":"Wilson and Ruff","shortCitationYear":1999,"referenceCode":"B99WIL01NACA","lastModified":"2020-02-25T18:12:03.647505Z"},{"id":106746,"citation":"Woodward, D. K. 1977. Status and ecology of the beaver (<i>Castor canadensis</i>) in South Carolina with emphasis on the Piedmont region. M.S. thesis, Clemson University, Clemson, South Carolina. 208 pp.","shortCitationAuthor":"Woodward","shortCitationYear":1977,"referenceCode":"U77WOO01NAUS","lastModified":"2021-11-06T21:38:45.082784Z"},{"id":138685,"citation":"Yeager, L. E., and R. R. Hill. 1954. Beaver management problems on western public lands. Transactions of the North American Wildlife and Natural Resources Conference 19:462-479.","shortCitationAuthor":"Yeager and Hill","shortCitationYear":1954,"referenceCode":"A54YEA01NAUS","lastModified":"2020-02-25T18:14:06.86812Z"},{"id":155410,"citation":"Yeager, L. E., and W. H. Rutherford. 1957. An ecological basis for beaver management in the Rocky Mountain region. Transactions of the North American Wildlife and Natural Resources Conference 22:269-299.","shortCitationAuthor":"Yeager and Rutherford","shortCitationYear":1957,"referenceCode":"A57YEA01NAUS","lastModified":"2020-02-25T18:14:06.852503Z"}],"otherCommonNames":[{"id":144356,"name":"American beaver","language":"EN"},{"id":136169,"name":"Beaver","language":"EN"},{"id":136170,"name":"Castor du Canada","language":"FR"},{"id":136168,"name":"North American Beaver","language":"EN"}],"speciesGlobal":{"elementGlobalId":100922,"cites":null,"cosewic":null,"fwsRegion":null,"genusSize":{"id":2,"genusSizeDescEn":"Very small genus","genusSizeDescEs":"Un género muy pequeño","genusSizeDescFr":"Très petit genre"},"jurisEndem":{"id":5,"jurisEndemDescEn":"occurs (regularly, as a native taxon) in multiple nations","jurisEndemDescEs":"Se encuentra en varias naciones (de manera regular, como un taxón nativo)","jurisEndemDescFr":"Se trouve dans plusieurs nations (de façon régulière, tel un taxon indigène)"},"nomenclaturallyEst":null,"usesa":null,"informalTaxonomy":{"informalTaxonomyId":6,"level1":"Animals","level2":"Vertebrates","level3":"Mammals","level":3,"hasChildren":false,"parentId":2,"distributionStatus":"complete","displayOrder":1090},"parentSpecies":null,"infraspecies":false,"kingdom":"Animalia","phylum":"Craniata","taxclass":"Mammalia","taxorder":"Rodentia","family":"Castoridae","genus":"Castor","americanFisheriesStatus":null,"americanFisheriesStatusDate":null,"saraStatus":null,"saraStatusDate":null,"cosewicDate":null,"interpretedCosewic":null,"cosewicComments":null,"usesaDate":null,"interpretedUsesa":null,"usesaComments":null,"completeDistribution":true,"synonyms":[],"infraspeciesList":[{"infraspeciesId":101398,"uniqueId":"ELEMENT_GLOBAL.2.101398","formattedScientificName":"<i>Castor canadensis phaeus</i>","scientificName":"Castor canadensis phaeus","primaryCommonName":"Admiralty Beaver","nsxUrl":null},{"infraspeciesId":1216072,"uniqueId":"ELEMENT_GLOBAL.2.1216072","formattedScientificName":"<i>Castor canadensis frondator</i>","scientificName":"Castor canadensis frondator","primaryCommonName":"Sonora Beaver","nsxUrl":null}],"ebarId":null,"ebarCanadianScope":false,"ebarGlobalScope":false,"ebarKbaGroup":"Mammals","caGeneralStatusId":"GS001601"},"speciesCharacteristics":{"elementGlobalId":100922,"reproductionComments":"Mating is monogamous. Outbreeding is the rule, with rare parent-progeny mating; matings between parent and offspring apparently occur only when a family unit is disrupted by the death of one adult (Taylor 1970, Svendsen 1980). In Ohio, Svendsen (1989) found that 56% of all pairs were formed in September, October, and November. Pair-bonds tended to last longer in areas with more stable conditions (lakes) than they did in comparatively unstable sites (streams). <br><br>Breeding (i.e., copulation) occurs January-March in the middle part of the range, mainly February-March in cold northern areas, mid-February in Newfoundland (Bergerud and Miller 1977), and over a longer season (late October-March) in the south (near the winter soltice in Mississippi; Wigley et al. 1983). <br><br>Gestation is thought to be 105-107 days, though also reported as about 128 days (Miller 1983) or around 100 days (Bergerud and Miller 1977). Parturition occurs in April, May, or June in Missouri (Schwartz and Schwartz 1981), April or May in Texas, generally late March and early April in Mississippi (Wigley et al. 1983), late May or early June in Newfoundland (Bergerud and Miller 1977), and June in Saskatchewan (Gunson 1970). In Ohio, Svendsen (1980) first heard the whining of kits in lodges in June. <br><br>Litter size ranges from one to nine, with three or four being typical in many areas. Factors influencing litter size include food supply, growing season, female size and age, and harvest rate. A female beaver produces one litter per year. Weaning occurs at an age of about six weeks and a weight of 4 pounds (1.8 kg). <br><br>In most cases, the young disperse from their family group in late winter or early spring, at an age of almost two years, before the new kits are born, or dispersal may occur later in summer. Some authors state that dispersal occurs at the end of the first year. Dispersal occurs over land and via waterways (Leege 1968). Apparently the young may remain in the family group longer than two years in high quality habitats and/or in habitats that are saturated with beavers (Boyce 1974, Gunson 1970, Bergerud and Miller 1977, Novakowski 1965). Dispersers often move to another area and begin a new pond. Sometimes they may return to their natal site (Svendsen 1980, Ryden 1988). <br><br>Survival of the young can be quite high in untrapped populations. Svendsen (1980) found that survival of the kits through their second summer was 95% (based on cohorts that lived long enough to emerge from their natal lodge). Some other studies also found that losses in the first year were very low, but other research indicates higher mortality rates (see Novak 1987a). <br><br>Compared to other rodents, beavers attain sexual maturity at a relatively late age. Females normally first give birth on or near their third birthday, and may remain productive for up to at least ten years (Stegeman 1954), though only a few live that long. Sometimes females breed when one (rarely) or two years old, though this is rare at the northern and southern range limits (Hill 1982). Males generally first breed at an age of about 21 months, though a variable proportion of yearlings may breed and sometimes older males may be functionally sterile.","ecologyComments":"A keystone species that has profound effects on aquatic and riparian ecosystems (Naiman et al. 1986). <br><br>In boreal systems, may influence 20-40% of the length of 2nd- to 5th-order streams (Ford and Naiman 1988). Open patches created by beaver in New York and Wisconsin varied from less than 0.5 ha to 30 ha (Remillard et al. 1987, Dickinson 1971, Knudsen 1962), but averaged less than 4 ha. <br><br>Among the many changes that occur with beaver activity are the following (see Johnston and Naiman 1987 and Naiman et al. 1988): <br><br>1. Storage of precipitation and reduced discharge variability (Naiman et al. 1986, Hill 1982). <br><br>2. Increased depth and surface area of water (Hill 1982, Naiman et al. 1986). <br><br>3. Increase in open canopy (Naiman et al. 1986)). <br><br>4. Reduction of riparian deciduous trees (Beier and Barrett 1987, NYDEC 1991). <br><br>5. Enhancement or degradation of fish habitat (Neff 1957, Gard 1961, Hill 1982, Churchill 1980, cited in Munther 1983). <br><br>6. Habitat enhancement for species dependent on wetlands or dead trees (Reese and Hair 1976, Hill 1982, Ermer 1988, Dieter and McCabe 1989, Arner and Hepp 1989, Dubec et al. 1988, 1990, NYDEC 1991, Novak 1987a). <br><br>7. Increased plankton productivity and an increase in aquatic insects (Naiman et al. 1986). <br><br>8. Increased trapping of sediment and decreased turbidity downstream (Naiman et al. 1986). <br><br>9. Enhancement of beaver food plants such as willow and alder (Slough and Sadleir 1977). <br><br>10. Increase in carbon and nutrients in the channel (Hodkinson 1975, Naiman et al. 1986, Naiman and Mellilo 1984, Francis et al. 1985). <br><br>11. Increased resistance of ecosystem to perturbation (Naiman et al. 1986). <br><br>Beaver ponds are a shifting mosaic of habitats, dependent on pond age and size, successional state, substrate, hydrology, and nutrients. In boreal regions, there is a complex pattern of ecosystem development that involves the formation of marshes, seasonally flooded meadows, and forested wetlands, which appear to persist in a somewhat stable condition for centuries (Naiman et al. 1988). Food shortage probably is the major factor affecting colony longevity (Hodgdon 1978). <br><br>Population Ecology: A typical 'colony' is a family group (Payne 1982) of 3-6 individuals, with one breeding female (Novak 1977). Typical densities range from 0.4 to 0.8 families per square kilometer (Naiman et al. 1986) or from 0.09 to 1.2 families per stream km (Voight et al. 1976); saturation densities 0.4-1.9 families per km. In Newfoundland, reach greatest density in early succession (Northcott 1964). In Massachusetts, density increased with increasing hardwoods and with decreasing gradient, watershed size, and stream width (Howard and Larson 1985). <br><br>Mortality Factors: Humans are the only significant predators in most areas. Wolves may prey on beavers when ungulate populations are low (Voight et al. 1976, Shelton and Peterson 1983). In some regions tularemia (the bacterium FRANCISELLA TULARENSIS) has caused large die-offs (see Novak 1987a, Addison et al. 1987). However, most unexploited populations have a low mortality rate (less than 5- 7%), and can grow quickly in areas with abundant resources. <br><br>Scent Marking and Territoriality: A family maintains a territory from which other unrelated beavers generally are thought to be excluded (see Hodgden 1978 for evidence to the contrary). An important component of this is the construction of scent mounds, which typically are placed along trails and canals, and on lodges, dams, and pond banks.","habitatComments":"Beavers inhabit permanent sources of water of almost any type in their range, which extends from arctic North America to the Gulf of Mexico and arid Southwest, and from sea level to over 3400 m in the mountains. They prefer low gradient streams (which they modify), ponds, and small mud-bottomed lakes with dammable outlets (Slough and Sadleir 1977, Beier and Barrett 1987, Novak 1987a, McComb et al. 1990). Beavers readily occupy artificial ponds, reservoirs, and canals if food is available. They generally avoid lakes with strong wave action and fast- moving streams. Waters with greatly fluctuating flow or water levels generally are poor habitat. In larger rivers (9th order or larger streams), beavers use floodplains and backwaters. In the north, they require water that is deep enough such that it does not freeze to the bottom and allows the accumulation of a substantial food pile beneath the ice. Beavers are associated with deciduous tree and shrub communities. In many situations beavers modify existing stream courses or other bodies of water and make them more suitable for their own use (see section below on dam building). They may occupy deep sections of streams and existing lakes or ponds without constructing a dam. <br><br>See Allen (1983) for a beaver habitat suitability index based on food and water characteristics. See Novak (1987a) for references to other models that have been developed in attempts to predict beaver family density. <br><br>Dam Construction Most dam building occurs April-June and especially August-October (Hill 1982), though repairs may be made at any time. In Quebec, the density of dams on small streams (4th order or less) averaged 10.6 per kilometer (range 8.6-16.0) (Naiman et al. 1986). In the northeastern U.S., a beaver family maintains an average of 2.5 dams. Generally trees, together with mud and rocks, supply the material for a dam. <br><br>Streams dammed by beavers typically are 2nd to 4th order streams; rarely do they build on 1st-order streams except at uncommonly high population densities. Dams in the main channel of streams of 5th order or larger often are destroyed by spring flooding (Naiman et al. 1986). In some areas (e.g. Missouri), dam building does not occur as commonly as in the north or west, perhaps due to the occurrence of deep swift rivers subject to severe flooding (Schwartz and Schwartz 1981). <br><br>Lodges <br><br>A characteristic beaver sign is the lodge, a hollow mound of tree branches (or, in the far north, mainly nonwoody material) and mud within which the beaver family sleeps and raises young. A lodge may be built against a bank, on an island, or in shallow water, but it must be near permanently deep water such that the entrance of the lodge is under water and so that the food cache can be reached even when the body of water is ice-covered. In bogs in northern Minnesota, beavers sometimes built lodges on the bog mat and many lodges were floating (Rebertus 1986). allowing for some ventilation. A family may maintain and use more than one lodge in summer in some areas (e.g., Colorado, Massachusetts). In some localities beavers use a different lodge each winter; it is more likely that the same lodge will be used if food in the area is abundant (Buech 1985). Beaver dens are not always in lodges. In some areas, beavers den in burrows in the banks of streams or lakes. This is common in areas subject to floods and fluctuating water levels. Beavers normally stay within 0.8 km of the den throughout the year (Schwartz and Schwartz 1981).","generalDescription":"The information in this section is from Miller (1983), Hill (1982), and Novak (1987a), unless otherwise indicated. <br><br>The beaver is the largest North American rodent; most adults weigh 16-23 kg (35-50 pounds), rarely 32-38 kg (70-85 pounds) or more. Kits weigh about 0.5 kg or a little less (1 pound) at birth (Hill 1982), when they are about 38 cm (15 inches) long (Schwartz and Schwartz 1981). The relationship between beaver age and mass is roughly as follows: < 0.5 years old, < 5 kg (11 pounds); 0.5-1.5 years old, 6-11 kg (13-24 pounds); 1.5-2.5 years old, 10- 13 kg (22-29 pounds); > 2.5 years old, > 14 kg (31 pounds). The preceding weight-age data are often accurate, but it must be realized that weight is influenced by various factors other than age. <br><br>The total length of a beaver varies with age as follows: yearlings are 26-34 inches; adults of 2-3 years, 35-40 inches; older adults, 47+ inches (maximum about 4.5 feet). in the warmer months and generally ends at age 4-5 years. <br><br>Pelage color varies geographically from yellowish-brown to black (this range of color may be found in a single watershed). There is one annual molt. The pelt is prime from late fall to early spring. <br><br>The sexes are difficult to distinguish externally. Hodgen (1978) provided information on sexing beavers by their behavior in a live trap. See Novak (1987a) for additional references on sexing methods.","diagnosticCharacteristics":"An inexperienced observer could mistake a muskrat (ONDATRA ZIBETHICUS), round-tailed muskrat (NEOFIBER ALLENI) or a nutria (MYOCASTOR COYPUS) for a beaver, but these other rodents do not have a broad flattened tail.","speciesMarineHabitats":[],"speciesTerrestrialHabitats":[],"speciesRiverineHabitats":[{"cagRiverineHabId":-102733,"riverineHabitat":{"id":1,"riverineHabitatDescEn":"BIG RIVER","riverineHabitatDescEs":"RÍO GRANDE","riverineHabitatDescFr":"GRANDE RIVIÈRE","displayOrder":1}},{"cagRiverineHabId":-102734,"riverineHabitat":{"id":2,"riverineHabitatDescEn":"MEDIUM RIVER","riverineHabitatDescEs":"RÍO MEDIANO","riverineHabitatDescFr":"MOYENNE RIVIÈRE","displayOrder":2}},{"cagRiverineHabId":-102735,"riverineHabitat":{"id":3,"riverineHabitatDescEn":"CREEK","riverineHabitatDescEs":"ARROYO","riverineHabitatDescFr":"RUISSEAU","displayOrder":3}},{"cagRiverineHabId":-102736,"riverineHabitat":{"id":9,"riverineHabitatDescEn":"Pool","riverineHabitatDescEs":"Piscina","riverineHabitatDescFr":"Fosse","displayOrder":9}}],"speciesPalustrineHabitats":[{"cagPalusHabId":-101437,"palustrineHabitat":{"id":6,"palustrineHabitatDescEn":"Riparian","palustrineHabitatDescEs":"Ribereño","palustrineHabitatDescFr":"Riverain","displayOrder":6}}],"speciesLacustrineHabitats":[{"cagLacusHabId":-100362,"lacustrineHabitat":{"id":1,"lacustrineHabitatDescEn":"Deep water","lacustrineHabitatDescEs":"Aguas profundas","lacustrineHabitatDescFr":"Eau profonde","displayOrder":1}},{"cagLacusHabId":-100363,"lacustrineHabitat":{"id":2,"lacustrineHabitatDescEn":"Shallow water","lacustrineHabitatDescEs":"Aguas poco profundas","lacustrineHabitatDescFr":"Eau peu profonde","displayOrder":2}}],"speciesSubterraneanHabitats":[],"speciesEstuarineHabitats":[]},"primaryReference":{"id":1151804,"citation":"American Society of Mammalogists (ASM). 2025. Mammal Diversity Database (Version 1.13) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.10595931. Online. Available: https://www.mammaldiversity.org/","shortCitationAuthor":"American Society of Mammalogists (ASM)","shortCitationYear":2025,"referenceCode":"W25ASM01NAUS","lastModified":"2025-04-04T21:45:15.526109Z"},"predecessors":[{"predecessorId":112708,"elCode":"AMAFE01012","name":"Castor canadensis frondator","formattedName":"<i>Castor canadensis frondator</i>","classficationCode":null,"uniqueId":"ELEMENT_GLOBAL.2.1216072","lineageDate":null,"nsxUrl":null},{"predecessorId":112709,"elCode":"AMAFE01011","name":"Castor canadensis phaeus","formattedName":"<i>Castor canadensis phaeus</i>","classficationCode":null,"uniqueId":"ELEMENT_GLOBAL.2.101398","lineageDate":null,"nsxUrl":null}],"elementGlobalThreatAssessments":[{"elementGlobalThreatAssessId":16888,"iucnThreatCategory":{"id":5,"iucnThreatCategoryCd":"2","iucnThreatCategoryDescEn":"Agriculture & aquaculture","iucnThreatCategoryDescEs":null,"iucnThreatCategoryDescFr":null,"displayValueEn":"2 - Agriculture & aquaculture","displayValueEs":null,"displayValueFr":null,"displayOrder":50,"iucnThreat":"Y","parentThreatId":null,"iucnThreatLevel":1},"iucnThreatScope":null,"iucnThreatSeverity":null,"iucnThreatTiming":{"id":1,"iucnThreatTimingDescEn":"High: Continuing","iucnThreatTimingDescEs":null,"iucnThreatTimingDescFr":null,"displayValueEn":"High (continuing)","displayValueEs":null,"displayValueFr":null,"displayOrder":1},"threatImpactCalc":null},{"elementGlobalThreatAssessId":16889,"iucnThreatCategory":{"id":6,"iucnThreatCategoryCd":"2.1","iucnThreatCategoryDescEn":"Annual & perennial non-timber crops","iucnThreatCategoryDescEs":null,"iucnThreatCategoryDescFr":null,"displayValueEn":"2.1 - Annual & perennial non-timber crops","displayValueEs":null,"displayValueFr":null,"displayOrder":60,"iucnThreat":"Y","parentThreatId":5,"iucnThreatLevel":2},"iucnThreatScope":null,"iucnThreatSeverity":null,"iucnThreatTiming":{"id":1,"iucnThreatTimingDescEn":"High: Continuing","iucnThreatTimingDescEs":null,"iucnThreatTimingDescFr":null,"displayValueEn":"High (continuing)","displayValueEs":null,"displayValueFr":null,"displayOrder":1},"threatImpactCalc":null},{"elementGlobalThreatAssessId":16891,"iucnThreatCategory":{"id":19,"iucnThreatCategoryCd":"5","iucnThreatCategoryDescEn":"Biological resource use","iucnThreatCategoryDescEs":null,"iucnThreatCategoryDescFr":null,"displayValueEn":"5 - Biological resource use","displayValueEs":null,"displayValueFr":null,"displayOrder":330,"iucnThreat":"Y","parentThreatId":null,"iucnThreatLevel":1},"iucnThreatScope":null,"iucnThreatSeverity":null,"iucnThreatTiming":{"id":1,"iucnThreatTimingDescEn":"High: Continuing","iucnThreatTimingDescEs":null,"iucnThreatTimingDescFr":null,"displayValueEn":"High (continuing)","displayValueEs":null,"displayValueFr":null,"displayOrder":1},"threatImpactCalc":null},{"elementGlobalThreatAssessId":16892,"iucnThreatCategory":{"id":20,"iucnThreatCategoryCd":"5.1","iucnThreatCategoryDescEn":"Hunting & collecting terrestrial animals","iucnThreatCategoryDescEs":null,"iucnThreatCategoryDescFr":null,"displayValueEn":"5.1 - Hunting & collecting terrestrial animals","displayValueEs":null,"displayValueFr":null,"displayOrder":340,"iucnThreat":"Y","parentThreatId":19,"iucnThreatLevel":2},"iucnThreatScope":null,"iucnThreatSeverity":null,"iucnThreatTiming":{"id":1,"iucnThreatTimingDescEn":"High: Continuing","iucnThreatTimingDescEs":null,"iucnThreatTimingDescFr":null,"displayValueEn":"High (continuing)","displayValueEs":null,"displayValueFr":null,"displayOrder":1},"threatImpactCalc":null}]}