Egretta thula - (Molina, 1782)
Snowy Egret
Other English Common Names: snowy egret
Other Common Names: Garcinha-Branca, Garça-Pequena
Taxonomic Status: Accepted
Related ITIS Name(s): Egretta thula (Molina, 1782) (TSN 174813)
French Common Names: aigrette neigeuse
Spanish Common Names: Garcita Blanca, Garceta Pie-Dorado
Unique Identifier: ELEMENT_GLOBAL.2.100485
Element Code: ABNGA06030
Informal Taxonomy: Animals, Vertebrates - Birds - Wading Birds
Image 7491

© Larry Master

 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Aves Pelecaniformes Ardeidae Egretta
Genus Size: C - Small genus (6-20 species)
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Concept Reference
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Concept Reference: American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.
Concept Reference Code: B98AOU01NAUS
Name Used in Concept Reference: Egretta thula
Taxonomic Comments: May constitute a superspecies with E. garzetta, E. gularis, and E. dimorpha (AOU 1998). Frequently placed in genus leucophoyx (AOU 1983).
Conservation Status
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NatureServe Status

Global Status: G5
Global Status Last Reviewed: 07Apr2016
Global Status Last Changed: 20Nov1996
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Reasons: Very large range (U.S. to southern South America), relatively secure on a global level; threatened in some areas by loss/degradation of wetland habitat.
Nation: United States
National Status: N5B,N5N (05Jan1997)
Nation: Canada
National Status: N1B,N1M (02Jan2018)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Alabama (S4), Arizona (S1B,S4N), Arkansas (S2B), California (S4), Colorado (S2B), Connecticut (S1B), Delaware (S1B), District of Columbia (S2N), Florida (S3), Georgia (S4), Idaho (S1B), Illinois (S1), Indiana (SNA), Iowa (S2N), Kansas (S2B), Kentucky (S1B), Louisiana (S4N,S5B), Maine (S3B), Maryland (S3B), Massachusetts (S2B,S4N), Michigan (SNRN), Minnesota (SNA), Mississippi (S4B,S1N), Missouri (S1), Montana (SNA), Navajo Nation (S4M), Nebraska (SNRN), Nevada (S4B), New Hampshire (SNA), New Jersey (S3B,S4N), New Mexico (S3B,S4N), New York (S2S3), North Carolina (S2S3B,S3N), Ohio (S1), Oklahoma (S5B), Oregon (S2B), Rhode Island (S1B), South Carolina (SNRB,SNRN), South Dakota (S2B), Tennessee (S2B,S3N), Texas (S5B), Utah (S4S5B), Virginia (S2B,S3N), Washington (SNA), Wyoming (S3B)
Canada Ontario (SNA), Saskatchewan (S1B)

Other Statuses

IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent: >2,500,000 square km (greater than 1,000,000 square miles)
Range Extent Comments: BREEDING: northern California, southern Idaho, Kansas, lower Mississippi Valley, and Gulf and Atlantic coasts north to Maine, south through Mexico and the Antilles to South America (to southern Chile and central Argentina). See Spendelow and Patton (1988) for information on the distribution and abundance of coastal U.S. breeding colonies. NON-BREEDING: northern California, southwestern Arizona, Gulf Coast, and South Carolina southward through the breeding range. In the U.S., areas with the highest densities in winter include the Gulf Coast along the Texas-Louisiana border, the mouth of the Mississippi River, the lower Colorado River, and Florida (Root 1988). Wanders irregularly outside usual range; rare straggler to Hawaii.

Number of Occurrences: > 300

Population Size: Unknown
Population Size Comments: Inadequate data on numbers at the breeding sites make it difficult to judge abundance.

Overall Threat Impact Comments: Threats include clearing of flood plain forests, loss and degradation of wetlands. Reduced reproductive success in Idaho was attributed to DDE residues accumulated in the nonbreeding season in Mexico (Findholt 1984).

Short-term Trend Comments: Populations in the south-central U.S. may be benefiting from crayfish aquaculture; bird population increases may be related to favorable foraging opportunities afforded by expanding crayfish aquaculture (Fleury and Sherry 1995).

Other NatureServe Conservation Status Information

Protection Needs: Protect breeding sites and foraging areas.

Distribution
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Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDING: northern California, southern Idaho, Kansas, lower Mississippi Valley, and Gulf and Atlantic coasts north to Maine, south through Mexico and the Antilles to South America (to southern Chile and central Argentina). See Spendelow and Patton (1988) for information on the distribution and abundance of coastal U.S. breeding colonies. NON-BREEDING: northern California, southwestern Arizona, Gulf Coast, and South Carolina southward through the breeding range. In the U.S., areas with the highest densities in winter include the Gulf Coast along the Texas-Louisiana border, the mouth of the Mississippi River, the lower Colorado River, and Florida (Root 1988). Wanders irregularly outside usual range; rare straggler to Hawaii.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
NOTE: The maps for birds represent the breeding status by state and province. In some jurisdictions, the subnational statuses for common species have not been assessed and the status is shown as not-assessed (SNR). In some jurisdictions, the subnational status refers to the status as a non-breeder; these errors will be corrected in future versions of these maps. A species is not shown in a jurisdiction if it is not known to breed in the jurisdiction or if it occurs only accidentally or casually in the jurisdiction. Thus, the species may occur in a jurisdiction as a seasonal non-breeding resident or as a migratory transient but this will not be indicated on these maps. See other maps on this web site that depict the Western Hemisphere ranges of these species at all seasons of the year.
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AL, AR, AZ, CA, CO, CT, DC, DE, FL, GA, IA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, NE, NH, NJ, NM, NN, NV, NY, OH, OK, OR, RI, SC, SD, TN, TX, UT, VA, WA, WY
Canada ON, SK

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: NatureServe, 2002


U.S. Distribution by County Help
State County Name (FIPS Code)
AZ Maricopa (04013), Yuma (04027)
CA Colusa (06011), Contra Costa (06013), Del Norte (06015), Fresno (06019), Glenn (06021), Humboldt (06023), Kern (06029), Marin (06041), Riverside (06065), Sacramento (06067), Santa Clara (06085), Solano (06095), Stanislaus (06099)
CO Adams (08001), Alamosa (08003), Delta (08029), La Plata (08067), Mesa (08077)*, Rio Grande (08105), Saguache (08109)
CT Fairfield (09001), Middlesex (09007), New Haven (09009), New London (09011)
DE Kent (10001), New Castle (10003), Sussex (10005)
FL Alachua (12001), Baker (12003), Bay (12005), Brevard (12009), Broward (12011), Calhoun (12013), Charlotte (12015), Citrus (12017), Clay (12019), Collier (12021), Columbia (12023), DeSoto (12027), Dixie (12029), Duval (12031), Escambia (12033), Franklin (12037), Glades (12043), Gulf (12045), Hamilton (12047), Hardee (12049), Hendry (12051), Hernando (12053), Highlands (12055)*, Hillsborough (12057), Holmes (12059), Indian River (12061), Jackson (12063), Jefferson (12065), Lake (12069), Lee (12071), Manatee (12081), Marion (12083), Martin (12085), Miami-Dade (12086), Monroe (12087), Nassau (12089), Okeechobee (12093), Orange (12095)*, Osceola (12097), Palm Beach (12099), Pasco (12101), Pinellas (12103), Polk (12105), Putnam (12107), Sarasota (12115), St. Johns (12109), St. Lucie (12111), Sumter (12119), Suwannee (12121), Taylor (12123), Volusia (12127), Wakulla (12129)
ID Ada (16001), Bannock (16005), Bear Lake (16007), Bingham (16011), Blaine (16013), Bonneville (16019), Camas (16025), Canyon (16027), Caribou (16029), Cassia (16031), Clark (16033), Elmore (16039), Franklin (16041), Fremont (16043), Gem (16045), Gooding (16047), Jefferson (16051), Madison (16065), Minidoka (16067), Oneida (16071), Owyhee (16073), Payette (16075), Power (16077), Twin Falls (16083)
IL Cook (17031)*, St. Clair (17163)*
KS Barton (20009), Linn (20107), Reno (20155), Sedgwick (20173), Stafford (20185)
KY Lyon (21143)
MO Mississippi (29133), Pemiscot (29155), Scott (29201)
MS Hancock (28045), Harrison (28047), Jackson (28059)
NC Brunswick (37019), Carteret (37031), Columbus (37047), Currituck (37053), Dare (37055), Hyde (37095), New Hanover (37129), Robeson (37155)
NJ Atlantic (34001), Cape May (34009), Hudson (34017), Ocean (34029)
NY Bronx (36005), Kings (36047), Nassau (36059), Richmond (36085), Suffolk (36103), Westchester (36119)
OH Lucas (39095)
OR Harney (41025)*, Klamath (41035)*, Lake (41037)*
RI Newport (44005), Washington (44009)
SD Bennett (46007), Brookings (46011), Brown (46013), Brule (46015), Charles Mix (46023), Codington (46029), Day (46037), Hyde (46069), Kingsbury (46077), Lake (46079)*, Marshall (46091)
VA Accomack (51001), Northampton (51131)
WY Albany (56001), Campbell (56005), Carbon (56007), Converse (56009), Fremont (56013), Goshen (56015), Hot Springs (56017), Johnson (56019), Laramie (56021), Lincoln (56023), Natrona (56025), Park (56029), Sublette (56035), Sweetwater (56037), Teton (56039), Uinta (56041)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 Lower Connecticut (01080205)+, Narragansett (01090004)+, Pawcatuck-Wood (01090005)+, Quinnipiac (01100004)+
02 Bronx (02030102)+, Sandy Hook-Staten Island (02030104)+, Northern Long Island (02030201)+, Southern Long Island (02030202)+, Long Island Sound (02030203)+, Delaware Bay (02040204)+, Broadkill-Smyrna (02040207)+, Mullica-Toms (02040301)+, Great Egg Harbor (02040302)+, Chincoteague (02040303)+, Eastern Lower Delmarva (02040304)+, Pokomoke-Western Lower Delmarva (02080111)+
03 Albemarle (03010205)+, Pamlico Sound (03020105)+, Lower Neuse (03020204)+, White Oak River (03020301)+, Lower Cape Fear (03030005)+, Lumber (03040203)+, Waccamaw (03040206)+, St. Marys (03070204)+, Nassau (03070205)+, Upper St. Johns (03080101)+, Oklawaha (03080102)+, Lower St. Johns (03080103)+, Daytona - St. Augustine (03080201)+, Cape Canaveral (03080202)+, Vero Beach (03080203)+, Kissimmee (03090101)+, Western Okeechobee Inflow (03090103)+, Lake Okeechobee (03090201)+*, Everglades (03090202)+, Florida Bay-Florida Keys (03090203)+, Big Cypress Swamp (03090204)+, Caloosahatchee (03090205)+, Florida Southeast Coast (03090206)+, Peace (03100101)+, Myakka (03100102)+, Charlotte Harbor (03100103)+, Sarasota Bay (03100201)+, Manatee (03100202)+, Alafia (03100204)+, Hillsborough (03100205)+, Tampa Bay (03100206)+, Crystal-Pithlachascotee (03100207)+, Withlacoochee (03100208)+, Econfina-Steinhatchee (03110102)+, Upper Suwannee (03110201)+, Santa Fe (03110206)+, Apalachee Bay-St. Marks (03120001)+, Apalachicola (03130011)+, New (03130013)+, Apalachicola Bay (03130014)+, St. Andrew-St. Joseph Bays (03140101)+, Perdido Bay (03140107)+, Lower Choctawhatchee (03140203)+, Pascagoula (03170006)+, Mississippi Coastal (03170009)+, Lower Pearl. Mississippi (03180004)+
04 Little Calumet-Galien (04040001)+*
05 Lower Cumberland (05130205)+
07 Cahokia-Joachim (07140101)+*
08 Lower Mississippi-Memphis (08010100)+, New Madrid-St. Johns (08020201)+, Little River Ditches (08020204)+
10 Madison (10020007)+, Little Wind (10080002)+, Popo Agie (10080003)+, Lower Wind (10080005)+, Badwater (10080006)+, Upper Bighorn (10080007)+, Dry (10080011)+, North Fork Shoshone (10080012)+, Shoshone (10080014)+, Clear (10090206)+, Little Powder (10090208)+, Upper Belle Fourche (10120201)+, Fort Randall Reservoir (10140101)+, Medicine Knoll (10140103)+, Little White (10140203)+, Upper James (10160003)+, Mud (10160005)+, Lewis and Clark Lake (10170101)+, South Big Sioux Coteau (10170103)+, Middle Big Sioux Coteau (10170201)+, Upper Big Sioux (10170202)+, Lower Big Sioux (10170203)+*, Upper North Platte (10180002)+, Medicine Bow (10180004)+, Sweetwater (10180006)+, Middle North Platte-Casper (10180007)+, Middle North Platte-Scotts Bluff (10180009)+, Upper Laramie (10180010)+, Horse (10180012)+, Middle South Platte-Cherry Creek (10190003)+, Crow (10190009)+, Lower Marais Des Cygnes (10290102)+
11 Rattlesnake (11030009)+, Gar-Peace (11030010)+, Cow (11030011)+, Middle Arkansas-Slate (11030013)+
13 Alamosa-Trinchera (13010002)+, Saguache (13010004)+
14 Colorado headwaters-Plateau (14010005)+*, Lower Gunnison (14020005)+, Upper Green (14040101)+, New Fork (14040102)+, Upper Green-Slate (14040103)+, Big Sandy (14040104)+, Bitter (14040105)+, Upper Green-Flaming Gorge Reservoir (14040106)+, Blacks Fork (14040107)+, Muddy (14040108)+, Great Divide closed basin (14040200)+, Little Snake (14050003)+, Muddy (14050004)+, Animas (14080104)+
15 Yuma Desert (15030108)+, Lower Gila-Painted Rock Reservoir (15070101)+, Hassayampa (15070103)+, Lower Gila (15070201)+
16 Upper Bear (16010101)+, Central Bear (16010102)+, Bear Lake (16010201)+, Middle Bear (16010202)+, Lower Bear-Malad (16010204)+
17 Snake headwaters (17040101)+, Gros Ventre (17040102)+, Greys-Hobock (17040103)+, Idaho Falls (17040201)+, Upper Henrys (17040202)+, Lower Henrys (17040203)+, Teton (17040204)+, Willow (17040205)+, American Falls (17040206)+, Blackfoot (17040207)+, Portneuf (17040208)+, Lake Walcott (17040209)+, Raft (17040210)+, Upper Snake-Rock (17040212)+, Salmon Falls (17040213)+, Beaver-Camas (17040214)+, Camas (17040220)+, Little Wood (17040221)+, C. J. Idaho (17050101)+, Middle Snake-Succor (17050103)+, Upper Owyhee (17050104)+, Lower Boise (17050114)+, Middle Snake-Payette (17050115)+, Payette (17050122)+, Chetco (17100312)+, Harney-Malheur Lakes (17120001)+*, Silvies (17120002)+*, Donner Und Blitzen (17120003)+*, Silver (17120004)+*, Summer Lake (17120005)+*, Warner Lakes (17120007)+*, Guano (17120008)+*
18 Smith (18010101)+, Mad-Redwood (18010102)+, Williamson (18010201)+*, Upper Klamath Lake (18010203)+*, Sacramento-Stone Corral (18020104)+, Upper Coon-Upper Auburn (18020161)+, Middle Kern-Upper Tehachapi- (18030003)+, Upper Poso (18030004)+, Upper Deer-Upper White (18030005)+, Upper Dry (18030009)+, Tulare-Buena Vista Lakes (18030012)+, Middle San Joaquin-Lower (18040002)+, Suisun Bay (18050001)+, San Pablo Bay (18050002)+, San Francisco Bay (18050004)+, Salton Sea (18100204)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A large wading bird (egret).
General Description: A small white wading bird with a slim, pointed, black bill; long legs are all black or black with yellow-green on the back side (juveniles); toes yellow; breeding adult has long plumes on head, neck, and back; lores yellow, turning red in adults during breeding season; average length 61 cm, wingspan 104 cm.
Diagnostic Characteristics: Differs from great egret in being much smaller (length 61 cm vs. 99 cm) and in having a black bill rather than a yellow one. Differs from immature little blue heron in having predominantly dark legs (vs. dull yellow), a slimmer mostly black bill (vs. two-toned with gray base and dark tip), and usually paler wing tips. Differs from cattle egret in being larger (length 61 cm vs. 51 cm), slim rather than stocky, and in having a black bill (vs. yellow or red-orange) and predominantly dark legs (vs. yellow or dusky-red). Differs from rare white-phase adult reddish egret in having yellow toes and lacking a two-toned pink-and-black bill.
Reproduction Comments: Eggs are laid usually April to May or June in north; nests in Trinidad May-October, May-August in Costa Rica. Clutch size usually is 4-5 in north, 2-4 in south. Incubation lasts 18 days or longer, by both sexes. Young leave nest at 20-25 days. May first breed at one year. Often nests in large colonies.
Ecology Comments: Usually occurs in loose groups. Roosts usually communally.
Non-Migrant: Y
Locally Migrant: Y
Long Distance Migrant: Y
Mobility and Migration Comments: Migratory in north. Northern birds winter largely in Middle America (Stiles and Skutch 1989).
Estuarine Habitat(s): Bay/sound, Herbaceous wetland, Lagoon, River mouth/tidal river, Scrub-shrub wetland, Tidal flat/shore
Riverine Habitat(s): Low gradient
Lacustrine Habitat(s): Shallow water
Palustrine Habitat(s): FORESTED WETLAND, HERBACEOUS WETLAND, Riparian
Habitat Comments: Marshes, lakes, ponds, lagoons, mangroves, and shallow coastal habitats.

Nests in trees or shrubs or, in some areas, on ground or in marsh vegetation. Often nests with other colonial water birds. Nests over water or ground. See references in Spendelow and Patton (1988) for further details.

Adult Food Habits: Carnivore, Invertivore, Piscivore
Immature Food Habits: Carnivore, Invertivore, Piscivore
Food Comments: Eats small fishes, frogs, lizards, snakes, crustaceans, worms, snails, and insects; forages actively in shallow water, sometimes in fields. (Palmer 1962). May forage in coordinated groups in coastal areas (Costa Rica, Stiles and Skutch 1989).
Adult Phenology: Crepuscular, Diurnal
Immature Phenology: Crepuscular, Diurnal
Phenology Comments: Forages during daylight (Powell 1987).
Colonial Breeder: Y
Length: 61 centimeters
Weight: 371 grams
Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation
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Group Name: Colonial Wading Birds

Use Class: Breeding
Subtype(s): Foraging Area, Breeding Colony
Minimum Criteria for an Occurrence: Evidence of historical breeding , or current and likely recurring breeding, at a given location, minimally a reliable observation of one or more breeding pairs in appropriate habitat. Small heron colonies (rookeries or heronries) are often ephemeral in nature; recommend tracking rookeries which maintain a minimum of 15 active nests over 2-3 years. Where concentrations of non-breeding individuals occur within the boundaries of a breeding occurrence (especially if augmented by migrants), consider creating a separate occurrence with Location Use Class 'Nonbreeding.'
Mapping Guidance: Map Foraging Areas in separate polygons from the breeding colony if they are separated from the colony by areas simply flown over on commuting routes.
Separation Barriers: None.
Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 10 km
Separation Justification: Occurrences include breeding colonies and foraging areas, but the separation distance pertains to breediing colonies. Hence, difference occurrences may overlap. Unsuitable habitat: upland areas, except those known to be used regularly for foraging (e.g., meadows used by great egrets).

Separation distance is an arbitrary compromise between the high mobility of these birds and the need for occurrences of practical size for conservation planning. Occurrences do not necessarily represent discrete populations or metapopulations.

Colony fidelity low in some species (e.g. Roseate Spoonbill, Dumas 2000; Glossy Ibis, Davis and Kricher 2000).

Feeding areas associated with a breeding colony (i.e. different features of the same occurrence) may be a number of kilometers away from the colony: averaging 12 kilometers for Roseate Spoonbill (Dumas 2000); 7.3 kilometers for Glossy Ibis (Davis and Kricher 2000); 2.8 to more than 5 kilometers for Snowy Egrets (Smith 1995).

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): 3 km
Inferred Minimum Extent Justification: A low mean foraging range size for this group.
Date: 28Oct2004
Author: Cannings, S., and G. Hammerson

Use Class: Nonbreeding
Subtype(s): Roost, Foraging area
Minimum Criteria for an Occurrence: Evidence of recurring presence of flocks of non-breeding birds (including historical), including non-breeding birds within the breeding season and breeding individuals outside the breeding season; and potential recurring presence at a given location. Normally only areas where concentrations greater than 10 birds occur regularly for at least 20 days per year would be deemed occurrences. Be cautious about creating occurrences for observations that may represent single events.
Separation Barriers: None.
Separation Distance for Unsuitable Habitat: 10 km
Separation Distance for Suitable Habitat: 10 km
Separation Justification: Separation distance arbitrary, set at 10 kilometers to define occurrences of manageable size for conservation purposes. Occurrences defined primarily on the basis of areas supporting concentrations of foraging birds, rather than on the basis of distinct populations.
Inferred Minimum Extent of Habitat Use (when actual extent is unknown): 3 km
Inferred Minimum Extent Justification: Based on foraging ranges from breeding rookeries.
Date: 19Apr2002
Author: Cannings, S.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 22Dec1994
NatureServe Conservation Status Factors Author: Qureshi, B. Partially revised by G. Hammerson.
Element Ecology & Life History Edition Date: 22Dec1994
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
Help
  • Alabama Ornithological Society. 2006. Field checklist of Alabama birds. Alabama Ornithological Society, Dauphin Island, Alabama. [Available online at http://www.aosbirds.org/documents/AOSChecklist_april2006.pdf ]

  • Allen, C. R., S. Demarais, and R. S. Lutz. 1994. Red imported fire ant impact on wildlife: an overview. The Texas Journal of Science 46(1):51-59.

  • American Ornithologists Union (AOU). 1998. Check-list of North American Birds. 7th edition. American Ornithologists Union, Washington, D.C. 829 pages.

  • American Ornithologists' Union (AOU). 1983. Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 pp.

  • American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.

  • Andersen, M.D. 2011. HUC10-based species range maps. Prepared by Wyoming Natural Diversity Database for use in the pilot WISDOM application operational from inception to yet-to-be-determined date of update of tool.

  • Andersen, M.D. 2011. Maxent-based species distribution models. Prepared by Wyoming Natural Diversity Database for use in the pilot WISDOM application operational from inception to yet-to-be-determined date of update of tool.

  • Andrews, R. R. and R. R. Righter. 1992. Colorado Birds. Denver Museum of Natural History, Denver. 442 pp.

  • Andrle, R. F., and J. R. Carrol, editors. 1988. The atlas of breeding birds in New York State. Cornell Univ., Ithaca, New York. 551 pp.

  • BirdLife International. 2004b. Threatened birds of the world 2004. CD ROM. BirdLife International, Cambridge, UK.

  • Braun, M. J., D. W. Finch, M. B. Robbins, and B. K. Schmidt. 2000. A field checklist of the birds of Guyana. Smithsonian Institution, Washington, D.C.

  • Brown, K.M., J.L. Tims, R.M Erwin, and M.E. Richmond. 2001. Changes in the nesting populations of colonial waterbirds in Jamaica Bay Wildlife Refuge, New York, 1974-1998. Northeastern Naturalist 8(3): 275-292.

  • Budliger, R.E., and G. Kennedy. 2005. Birds of New York State. Lone Pine Publishing, Auburn, WA. 384pp.

  • Bull, John. 1974. Birds of New York State. Doubleday, Garden City, New York. 655 pp.

  • Canadian Wildlife Service. 1995. Last Mountain Lake and Stalwart National Wildlife Areas: Bird Checklist - Fourth Edition. Environment Canada. Ottawa, ON.

  • Castro, I. and A. Phillips. 1996. A guide to the birds of the Galapagos Islands. Princeton University Press, Princeton, New Jersey, USA.

  • Colorado Bird Observatory. 1997. 1996 Reference Guide to the Monitoring and Conservation Status of Colorado's Breeding Birds. Colorado Bird Observatory, Colorado Division of Wildlife, Great Outdoors Colorado Trust Fund, and Partners, March 21, 1997.

  • Cooke, W.W. 1913. Distribution and migration of North American herons and their allies. U.S. Dept. Agri. Biol. Surv. Bull. No. 45. 70pp.

  • Curry, R., and G.D. Bryant. 1987. Snowy Egret: a new breeding species for Ontario and Canada. Ontario Birds, 5(2): 64-67.

  • Dale, E.M.S. 1941. Bird notes from London, Ontario. Canadian Field-Naturalist 55:1-4.

  • Dorn, Jane L. and R.D. Dorn. 1990. Wyoming Birds. Mountain West Publishing, Cheyenne.

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