Cardellina canadensis - (Linnaeus, 1766)
Canada Warbler
Other English Common Names: Canada warbler
Synonym(s): Wilsonia canadensis (Linnaeus, 1766)
Taxonomic Status: Accepted
Related ITIS Name(s): Wilsonia canadensis (Linnaeus, 1766) (TSN 178977)
French Common Names: paruline du Canada
Spanish Common Names: Chipe de Collar
Unique Identifier: ELEMENT_GLOBAL.2.100725
Element Code: ABPBX16030
Informal Taxonomy: Animals, Vertebrates - Birds - Perching Birds
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Aves Passeriformes Parulidae Cardellina
Genus Size: A - Monotypic genus
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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: Wilsonia canadensis
Taxonomic Comments: Formerly placed in the genus Wilsonia. Phylogenetic analyses of sequences of nuclear and mitochondrial DNA (Lovette et al. 2010) indicate that two species formerly placed in the genus Wilsonia (canadensis and pusilla)and both species formerly placed in the genus Ergaticus (rubra and versicolor) form a clade with Cardellina rubrifrons. The generic name Cardellina has priority for this clade (AOU 2011).
Conservation Status
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NatureServe Status

Global Status: G5
Global Status Last Reviewed: 07Apr2016
Global Status Last Changed: 03Dec1996
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Reasons: Large breeding range in North America; large population size; many occurrences; apparently has declined over the past several decades, probably as a result of forest maturation/fragmentation and loss of forested wetlands in the breeding range and habitat loss in the nonbreeding range.
Nation: United States
National Status: N5B (19Mar1997)
Nation: Canada
National Status: N4B,N3M (25Jan2018)

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 (SNRM), Arkansas (SNA), Colorado (SNA), Connecticut (S4B), Delaware (SNA), District of Columbia (S4N), Florida (SNA), Georgia (S4), Illinois (S1), Indiana (S2B), Iowa (S3N), Kansas (SNA), Kentucky (S3B), Louisiana (SNA), Maine (S4B), Maryland (S3B), Massachusetts (S5B), Michigan (S5), Minnesota (SNRB), Mississippi (SNA), Missouri (SNA), Nebraska (SNRN), New Hampshire (S5B), New Jersey (S3B), New York (S5B), North Carolina (S4B), North Dakota (SU), Ohio (S2), Oklahoma (S1N), Pennsylvania (S4B), Rhode Island (S4B), South Carolina (S3), South Dakota (SNA), Tennessee (S3B,S4N), Texas (S4), Vermont (S4B), Virginia (S3S4B), West Virginia (S3B), Wisconsin (S3B)
Canada Alberta (S3S4B), British Columbia (S3S4B), Manitoba (S4B), New Brunswick (S3S4B,S3S4M), Newfoundland Island (SNA), Northwest Territories (SUB), Nova Scotia (S3S4B), Ontario (S4B), Prince Edward Island (S2B), Quebec (S3S4), Saskatchewan (S5B), Yukon Territory (S1B)

Other Statuses

Canadian Species at Risk Act (SARA) Schedule 1/Annexe 1 Status: T (23Feb2010)
Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Threatened (25Apr2008)
Comments on COSEWIC: Most (80%) of the breeding range of this species occurs in Canada. While regional trends may vary, overall the species has experienced a significant long-term decline. This decline is particularly evident in the case of the species' Canadian range and there is no indication that this trend will be reversed. The reasons for the decline are unclear, but loss of primary forest on the wintering grounds in South America is a potential cause.

Designated Threatened in April 2008.

IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent: 20,000-2,500,000 square km (about 8000-1,000,000 square miles)
Range Extent Comments: Breeding range extends from southeastern Yukon, northeastern British Columbia, and northern Alberta across southern Canada to Nova Scotia, and south to southern Manitoba, northern Minnesota, Great Lakes region, southern Appalachians (to northern Georgia), northern New Jersey, southeastern New York, and southern New England (AOU 1998, Conway 1999).

Range during the boreal winter extends from Venezuela and northern Colombia south to Ecuador, southern Peru, and the Tepui region of northern Brazil, mostly in and east of the Andes, and rarely northward to Central America (AOU 1998, Conway 1999). Birdlife International (2014) estimates a range of 2.1 million square kilometers.

Area of Occupancy: >12,500 4-km2 grid cells
Area of Occupancy Comments: With a territorial size of about 1 hectare (Reitsma, et. al. 2010), its estimated population size of up to four million would easily put it past the 20,000 square kilometers for occupancy.

Number of Occurrences: 81 to >300
Number of Occurrences Comments: This species is represented by a large number of occurrences (subpopulations). It has an extremely large range and population size (Birdlife International, 2014), suggesting that the minimum number of EOs in this range is easily met

Population Size: >1,000,000 individuals
Population Size Comments: Total population size is unknown but certainly exceeds 100,000 and probably exceeds 1,000,000. Rich et al. (2004) estimated population size at 1,400,000. Partners in Flight (2013) estimate a population size of 4 million

Number of Occurrences with Good Viability/Integrity: Many (41-125)
Viability/Integrity Comments: At least several dozen occurrences likely have at least good estimated viability.

Overall Threat Impact: Medium
Overall Threat Impact Comments: Declines evident in Breeding Bird Survey data may be related to change in forest structure over the past century, combined with loss of forested wetlands (Conway 1999). Forest regeneration of previously farmed lands in the Northeast probably provided optimal habitat (forest with dense understory) in the early and mid-1900s, but continued forest maturation probably eliminated the understory, and habitat became less suitable for the Canada Warbler (Conway 1999). Additionally, a large area of forested wetlands in the Northeast were drained, filled, and developed between 1950 and 1980 (Tiner 1984). Infestations of the hemlock woolly adelgid have degraded or eliminated habitat in some areas. Miller (1999) reported that declines in Rhode Island may be related to the impingement of urban development on heavily forested landscapes. This species appears to be sensitive to forest fragmentation; density and probability of occurrence in a forest decline with forest area (reviewed by Conway 1999).

Loss of wintering habitat in the northern Andes region of South America may have contributed to the decline (Robinson 1997, Faccio et al. 1997). Diamond (1991) projected that from 1985 to 2000, 28 percent of wintering habitat would be lost. Declines in undisturbed breeding habitats in Vermont (Faccio et al. 1997) suggest the problem is more than loss of breeding habitat, unless there is an undiscovered link between the advancement of succession on those monitoring sites and the reported declines.

Regardless of location, habitat loss is a primary concern. No other major threats have been identified.

Short-term Trend: Decline of 10-30%
Short-term Trend Comments: Breeding Bird Survey (BBS) data indicate a very slow decline or relatively stable trend over the past 10 years or three generations. The latest BBS from 2002 - 2012 show a 1.4% annaul decline over that time period, for an overall decline of 15% (Sauer, et. al. 2014).

Long-term Trend: Decline of >30%
Long-term Trend Comments: Long-term trend (past 200 years) is unknown, but this species may have undergone a decline over the past several decades. Breeding Bird Survey (BBS) data indicate a significant survey-wide decline averaging 2.3% per year during 1966-2007; this amounts to a 61% decline over this time period. However, this species is detected in relatively low numbers during these surveys. For example, BBS abundance (average number of individuals per route) declined from 0.9 to 1.3 in the 1960s and early 1970s to 0.5 to 0.6 in 2000-2007. So although the percentage decline is high, the decline in absolute terms is only 0.3-0.8 individuals per route.

BBS data for 1966-2003 indicate that most declines were in the northern part of the range, whereas increasing trends occurred in much of the Great Lakes region and Appalachian Mountains. The latest BBS data from 1996 - 2012 show a 65% decline over that time period (Sauer, et.a l. 2014).

Intrinsic Vulnerability: Moderately vulnerable to not intrinsically vulnerable.
Intrinsic Vulnerability Comments: The Canada Warbler will utilize many types of forests during the breeding season but it is sensitive to forest fragmention and human disturbance (National Audubon Society, 2014). In southern part of range a major issue is loss of its nesting habitat due to the Wooly Adelgid.

Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.
Environmental Specificity Comments: Utilizes many forest types but prefer dense underground with high foliage density in the shrub layer (National Audubon Society, 2014).

Other NatureServe Conservation Status Information

Inventory Needs: Need to survey numbers and obtain trends of populations on wintering grounds (Reitsma, et. al. 2010).

Protection Needs: Several areas with potential Canada Warbler habitat have been proposed as protected areas in British Columbia (Cooper et al. 1997). State wetland regulations protect wooded swamp nesting habitats in most states, but not all forested wetlands are well delineated and thus many remain unprotected. Populations are probably not monitored effectively by common monitoring programs because of dense, wet, inaccessible breeding habitats. (Reitsma, et. al. 2010).

Distribution
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Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) Breeding range extends from southeastern Yukon, northeastern British Columbia, and northern Alberta across southern Canada to Nova Scotia, and south to southern Manitoba, northern Minnesota, Great Lakes region, southern Appalachians (to northern Georgia), northern New Jersey, southeastern New York, and southern New England (AOU 1998, Conway 1999).

Range during the boreal winter extends from Venezuela and northern Colombia south to Ecuador, southern Peru, and the Tepui region of northern Brazil, mostly in and east of the Andes, and rarely northward to Central America (AOU 1998, Conway 1999). Birdlife International (2014) estimates a range of 2.1 million square kilometers.

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, CO, CT, DC, DE, FL, GA, IA, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, NC, ND, NE, NH, NJ, NY, OH, OK, PA, RI, SC, SD, TN, TX, VA, VT, WI, WV
Canada AB, BC, MB, NB, NF, NS, NT, ON, PE, QC, SK, YT

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)
IN Jasper (18073), La Porte (18091), Lagrange (18087), Montgomery (18107)*, Newton (18111), Porter (18127), Steuben (18151)
KY Bell (21013), Harlan (21095)
ND Cavalier (38019)
NJ Cumberland (34011), Morris (34027), Passaic (34031), Somerset (34035), Sussex (34037), Warren (34041)
OH Ashland (39005), Columbiana (39029), Fairfield (39045), Geauga (39055), Hocking (39073), Holmes (39075), Jackson (39079), Knox (39083), Lake (39085), Lorain (39093), Summit (39153)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
02 Rondout (02020007)+, Hackensack-Passaic (02030103)+, Raritan (02030105)+, Middle Delaware-Mongaup-Brodhead (02040104)+, Middle Delaware-Musconetcong (02040105)+, Cohansey-Maurice (02040206)+
04 Little Calumet-Galien (04040001)+, St. Joseph (04050001)+, Huron-Vermilion (04100012)+, Cuyahoga (04110002)+, Ashtabula-Chagrin (04110003)+, Grand (04110004)+
05 Upper Ohio (05030101)+, Hocking (05030204)+, Mohican (05040002)+, Lower Scioto (05060002)+, Sugar (05120110)+*, Upper Cumberland (05130101)+
06 Powell (06010206)+
07 Kankakee (07120001)+, Iroquois (07120002)+
09 Lower Pembina River (09020316)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A small bird (wood warbler).
Reproduction Comments: Eggs are laid in May-June. Clutch size is three to five (usually four). Young are tended by both parents (Terres 1980, Harrison 1978).
Ecology Comments: This species appears to show positive numerical response to outbreaks of the spruce budworm (Crawford and Jennings 1989, Patten and Burger 1998), though it is not generally considered to be a "budworm specialist."
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: Y
Mobility and Migration Comments: Migration through Central America and eastern Mexico occurs in both fall and spring. This species is a common migrant in Costa Rica in early September-early November; uncommon transient in April-early May (Stiles and Skutch 1989). It is present in South America mostly in October-April (Ridgely and Tudor 1989). On Appledore Island, Maine, individuals have significantly longer stopovers in fall than in spring (Morris et al. 1994).
Palustrine Habitat(s): Bog/fen, FORESTED WETLAND, Riparian, SCRUB-SHRUB WETLAND
Terrestrial Habitat(s): Forest - Hardwood, Forest/Woodland, Shrubland/chaparral, Woodland - Conifer, Woodland - Hardwood, Woodland - Mixed
Habitat Comments: Breeding habitat includes moist thickets of woodland undergrowth (especially aspen-poplar), bogs, tall shrubbery along streams or near swamps, and deciduous second growth. Habitat is more specific in localized regions. For example, the species is limited to forested wetlands in Rhode Island (Miller 1999) and hemlock-dominated ravines in Ohio (Mitchell 1999). Habitat predictors in western Maryland included limited ground cover but high foliage density between 0.3 and 1 meter (Robbins et al. 1989). Habitat in Rhode Island also included limited ground cover (a negative correlation with deciduous foliage cover within 0.5 meter of the ground) and a thick shrub layer (a positive correlation with foliage cover between 2 and 4 meters; Mitchell 1999). In northeastern British Columbia this warbler is associated with wet, usually unstable slopes in deciduous or mixed forests with a well-developed shrub layer and considerable amounts of woody debris (Campbell et al. 2001). Nests are on or near the ground, among roots of fallen trees, in cavities in banks, or on ledges, sides of rocks, hummocks, stumps, or fallen logs, or on the ground under shrubbery (Harrison 1978).

In migration, this warbler uses various forest, woodland, scrub, and thicket habitats, mostly in humid areas. In winter, it occurs in forested areas of foothills and mountains.

Adult Food Habits: Invertivore
Immature Food Habits: Invertivore
Food Comments: Diet includes beetles, mosquitoes, flies, moths, smooth caterpillars, etc.
Adult Phenology: Diurnal
Immature Phenology: Diurnal
Length: 13 centimeters
Weight: 11 grams
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: Several decades of population declines have led to increasing concern. Habitat loss appears to be the major problem, both on breeding and wintering grounds. Preserves will need to protect large areas, whether they are sizable tracts of good habitat or smaller tracts of good habitat surrounded by forested buffer zones to limit the encroachment of development. Some site disturbance, to the extent that it promotes development of a dense shrub layer, may have positive effects in both breeding and non-breeding areas. Much basic research remains to be done.
Restoration Potential: Moderate, assuming threats can be fully understood. Habitat loss in South America may prove to be more difficult to address than habitat problems in North America due to economic and population pressures there.
Preserve Selection & Design Considerations: Miller (1999) determined that landscape predictors are stronger than habitat predictors in Rhode Island. Warbler presence was more significantly correlated with distance from paved roads and total length of paved roads in nearby forests than with habitat variables. This suggests that preserves should be established in heavily forested landscapes that are relatively undisturbed by human activity. Robbins et al. (1989) found that forest size was positively correlated with warbler presence, and they implied a minimum preserve size of 400 hectares. Miller (1999), however, found that poorly drained forest wetland patches as small as 6 hectares were used if they had sufficient upland forest buffer; suitable preserves could be based on these small tracts of appropriate habitat if the surrounding area excludes human disturbance.

Preserves should include well-developed shrub layers (high densities of foliage between 0.5 and 4 meters) and minimal ground cover. Mesic sites, especially those with sphagnum moss, are preferred. Studies suggest that some recent disturbance is preferable to undisturbed, mature forests (Titterington et al. 1979, Maurer et al. 1981, Adams and Hammond 1991, Christian et al. 1996, King and DeGraaf, in press; King, pers. comm.), although at least two produced conflicting evidence (Johnson and Brown 1990, DeGraaf et al. 1991). Less information is available to guide preserve design in wintering areas. Thick, shrubby habitat structure is similar to that of breeding areas, suggesting that preserves incorporate some disturbance, but no data are available to quantify this.

Management Requirements: Management treatments that increase shrub density while limiting ground cover will be most effective. Clearcuts and shelterwood cuts received more use than mature forest in northern New Hampshire (King and DeGraaf, in press). In general, populations decrease at the time of disturbance but expand as regeneration of the shrub layer occurs. In New York, abundance peaked 5-15 years after heavy logging (Webb et al. 1977). Selective thinning of the forest canopy, whether by natural events like insect infestations (Adams and Hammond 1991) or blowdown (Hall 1984), or by human activities like mechanical strip thinning of aspen stands (Christian et al. 1996), appear to be beneficial, at least until the return of canopy closure. Where clearcuts are done, the leaving of residual patches of trees may provide some benefits (Merrill et al. 1998). Probably because they reduce vegetation in the shrubby understory, large numbers of deer have a negative effect on populations (DeGraaf et al. 1991). Managers should permit deer harvest in order to prevent high ungulate densities.
Monitoring Requirements: Roadside surveys may undercount due to the bird's preference for roadless breeding habitat. Unlimited or 100-meter point-counts may overcount compared to other species due to the warbler's loud, clear song (Schieck 1997). Miller (1999) followed standard 50 meter fixed-radius, point-counts by playing one minute of taped songs.
Management Research Needs: The greatest need for information occurs on the wintering grounds, where habitat is rapidly disappearing but remains poorly understood. Population trends, important concentration areas for wintering birds, exact habitat requirements, and sensitivity to disturbance all require study (Conway 1999). More study should be undertaken of factors influencing breeding success, including the impacts of forested wetland losses, the effects of management treatments, and the impacts of predation and brood parasitism. Evidence that abundance is negatively correlated with the proximity of paved roads raises questions about what the ultimate cause(s) is of this negative effect (Miller 1999). Conway (1999) notes a need for basic information about biology, especially all aspects of breeding biology.
Biological Research Needs: Top priority should be to identify proximate and ultimate cause of observed population declines. Urgent need to survey numbers and trends of populations on wintering grounds, identify important wintering areas for conservation, and determine extent and rate of winter habitat loss. More research needed on extent of sensitivity to forest area, dependence on wetlands and effects of wetland loss on observed population declines. Need to determine extent and effects of brood parasitism on annual fecundity (Reitsma, et. al. 2010). We need basic information on biology, natural history, and habitat needs. Priorities: estimates of adult and brood survival, nesting success, frequency of renesting following failure, site fidelity, and recruitment; examine environmental or habitat factors affecting survival, nest success, renesting probability, site fidelity, and recruitment; more data on incubation and nestling periods; information on nestling growth and development; quantify seasonal diets; quantify existence and function of pair bonds during migration and on wintering grounds; extent of territoriality on winter grounds; extent and importance of joining mixed-species foraging flocks during winter. (Reitsma, et. al. 2010).
Population/Occurrence Delineation
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Group Name: Passerines

Use Class: Breeding
Subtype(s): Foraging Area, Nest Site, Nesting 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. Be cautious about creating EOs for observations that may represent single breeding events outside the normal breeding distribution.

Mapping Guidance: Breeding occurrences include nesting areas as well as foraging areas.

For swallows and other species that have separate nesting and foraging areas, separations are based on nest sites or nesting areas, not to locations of foraging individuals. For example, nesting areas separated by a gap larger than the separation distance are different occurrences, regardless of the foraging locations of individuals from those nesting areas. This separation procedure is appropriate because nesting areas are the critical aspect of swallow breeding occurrences, tend to be relatively stable or at least somwhat predictable in general location, and so are the basis for effective conservation; foraging areas are much more flexible and not necessarily static.

Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Significant dispersal and associated high potential for gene flow among populations of birds separated by tens of kilometers (e.g., Moore and Dolbeer 1989), and increasing evidence that individuals leave their usual home range to engage in extrapair copulations, as well as long foraging excursions of some species, make it difficult to circumscribe occurrences on the basis of meaningful population units without occurrences becoming too large. Hence, a moderate, standardized separation distance has been adopted for songbirds and flycatchers; it should yield occurrences that are not too spatially expansive while also accounting for the likelihood of gene flow among populations within a few kilometers of each other.

Be careful not to separate a population's nesting areas and foraging areas as different occurrences; include them in the same occurrence even if they are more than 5 km apart. Mean foraging radius (from nesting area) of Brown-headed Cowbird females was 4.0 kilometers in California, 1.2 kilometers in Illinois-Missouri (Thompson 1994). Yellow-headed Blackbirds, Brewer's Blackbirds, and probably Red-winged Blackbirds all forage up to 1.6 kilometers away from breeding colony (Willson 1966, Horn 1968). In one study, Brewer's Blackbirds were found as far as 10 kilometers from nesting area (Williams 1952), but this may be unusual.

For swallows and other parrerines with similar behavioral ecology, separation distance pertains to nest sites or nesting colonies, not to locations of foraging individuals. For example, nesting areas separated by a gap of more than 5 km are different occurrences, regardless of the foraging locations of individuals from those nesting areas. This separation procedure is appropriate because nesting areas are the critical aspect of swallow breeding occurrences, tend to be relatively stable or at least somwhat predictable in general location, and so are the basis for effective conservation; foraging areas are much more flexible and not necessarily static.

Be cautious about creating EOs for observations that may represent single breeding events outside the normal breeding distribution.

Unsuitable habitat: Habitat not normally used for breeding/feeding by a particular species. For example, unsuitable habitat for grassland and shrubland birds includes forest/woodland, urban/suburban, and aquatic habitats. Most habitats would be suitable for birds with versatile foraging habits (e.g., most corvids).

Date: 10Sep2004
Author: Hammerson, G.

Use Class: Migratory stopover
Subtype(s): Foraging Area, Roost Site
Minimum Criteria for an Occurrence: For most passerines: Evidence of recurring presence of migrating individuals (including historical) and potential recurring presence at a given location; minimally a reliable observation of 25 birds in appropriate habitat.

For swallows: Evidence of recurring presence of migrating flocks (including historical) and potential recurring presence at a given location; minimally a reliable observation of 100 birds in appropriate habitat (e.g., traditional roost sites).

Occurrences should be locations where the species is resident for some time during the appropriate season; it is preferable to have observations documenting presence over at least 7 days annually.

EOs should not be described for species that are nomadic during nonbreeding season: e.g., Lark Bunting.

Be cautious about creating EOs for observations that may represent single events.

Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Separation distance somewhat arbitrary but intended to define occurrences of managable size for conservation purposes. Occurrences defined primarily on the basis of areas supporting concentrations of birds, rather than on the basis of distinct populations.

For swallows and other species with similar behavioral ecology, the separation distance pertains to communal roost sites rather than to foraging areas; the former tend to be more stable and specific over time than the latter.

Date: 03Sep2004
Author: Hammerson, G., and S. Cannings

Use Class: Nonbreeding
Subtype(s): Foraging Area, Roost Site
Minimum Criteria for an Occurrence: Any area used traditionally in the nonbreeding season (used for populations that are not resident in a location year-round). Minimally, reliable observations of 10 or more individuals in appropriate habitat for 20 or more days at a time. For G1-G3 species, observations of fewer individuals could constitute an occurrence of conservation value. Sites used during migration should be documented under the 'migratory stopover' location use class.

Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Separation distance is necessarily arbitrary but attempts to balance the high mobility of birds with the need for occurrences of reasonable spatial scope. Note that a population's roost sites and foraging areas are parts of the same occurrence, even if they are more than 5 km apart.

For swallows and other species with similar behavioral ecology, the separation distance pertains to communal roost sites rather than to foraging areas; the former tend to be more stable and specific over time than the latter.

Date: 03Sep2004
Author: Hammerson, G.

Use Class: Nonmigratory
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a particular location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals in or near appropriate habitat.

These occurrence specifications are used for nonmigratory populations of passerine birds.

Separation Barriers: None.
Separation Distance for Unsuitable Habitat: 5 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Significant dispersal and associated high potential for gene flow among populations of birds separated by tens of kilometers (e.g., Moore and Dolbeer 1989), and increasing evidence that individuals leave their usual home range to engage in extrapair copulations, as well as long foraging excursions of some species, make it difficult to circumscribe occurrences on the basis of meaningful population units without occurrences becoming too large. Hence, a moderate, standardized separation distance has been adopted for songbirds and flycatchers; it should yield occurrences that are not too spatially expansive while also accounting for the likelihood of gene flow among populations within a few kilometers of each other.

Be careful not to separate a population's nesting areas and breeding-season foraging areas as different occurrences; include them in the same occurrence even if they are more than 5 km apart. Blue jays have small summer home ranges but fly up to 4 kilometers to harvest mast (Tarvin and Woolfenden 1999). Flocks of pinyon jays range over 21-29 square kilometers (Ligon 1971, Balda and Bateman 1971); nesting and foraging areas may be widely separated. Tricolored blackbirds forage in flocks that range widely to more than 15 kilometers from the nesting colony (Beedy and Hamilton 1999).

Unsuitable habitat: Habitat not normally used for breeding/feeding by a particular species. For example, unsuitable habitat for grassland and shrubland birds includes forest/woodland, urban/suburban, and aquatic habitats. Most habitats would be suitable for birds with versatile foraging habits (e.g., most corvids).

Date: 10Sep2004
Author: Hammerson, G.
Notes: These specs pertain to nonmigratory species.
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: 18Nov2014
NatureServe Conservation Status Factors Author: Hammerson, G., D. Catlin, M. Koenen, and D. Mehlman; Modified by Jue, Dean K.
Management Information Edition Date: 24Dec1999
Management Information Edition Author: CATLIN, D.; REVISIONS BY M. KOENEN AND D.W. MEHLMAN
Management Information Acknowledgments: Steven Faccio of the Vermont Institute of Natural Science, David I. King of the University of Massachusetts, and Nicholas A. Miller of the University of Rhode Island all generously contributed copies of papers that were in preparation or difficult to acquire through the usual channels. The author also thanks Jane Fitzgerald of Partners in Flight, John Sauer of the U.S. Geological Survey's Patuxent Wildlife Research Center, and Giff Beaton and Bo Brown for answering questions and providing useful suggestions. Support for the preparation of this abstract was provided by the National Fish and Wildlife Foundation's Neotropical Migratory Bird Conservation Initiative, through challenge grant number 97-270 to The Nature Conservancy, Wings of the Americas Program. Matching funds for this grant were donated by Canon U.S.A., Inc.
Element Ecology & Life History Edition Date: 24Mar2009
Element Ecology & Life History Author(s): Hammerson, G., and D. Catlin

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

References
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  • Adams, D. A. and J. S. Hammond. 1991. Changes in forest vegetation, bird, and small mammal populations at Mount Mitchell, North Carolina--1959/62 and 1985. Journal of the Elisha Mitchell Scientific Society 107:3-12.

  • 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 ]

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NOTE: Full metadata for the Bird Range Maps of North America is available at:
http://www.natureserve.org/library/birdDistributionmapsmetadatav1.pdf.

Full metadata for the Mammal Range Maps of North America is available at:
http://www.natureserve.org/library/mammalsDistributionmetadatav1.pdf.

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