Pipilo maculatus - Swainson, 1827
Spotted Towhee
Other English Common Names: spotted towhee
Taxonomic Status: Accepted
Related ITIS Name(s): Pipilo maculatus Swainson, 1827 (TSN 554380)
French Common Names: tohi tacheté
Spanish Common Names: Toquí
Unique Identifier: ELEMENT_GLOBAL.2.104406
Element Code: ABPBX74080
Informal Taxonomy: Animals, Vertebrates - Birds - Perching Birds
Image 10753

© Dick Cannings

 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Aves Passeriformes Passerellidae Pipilo
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: Pipilo maculatus
Taxonomic Comments: Formerly regarded as conspecific with P. erythrophthalums (AOU 1998). Citing morphological, behavioral, and mtDNA differences (e.g., Ball and Avise 1992), AOU (1995) split the rufous-sided towhee into two species, P. erythrophthalmus (eastern towhee, central and eastern North America) and P. maculatus (spotted towhee, mainly west of the Great Plains). Limited hybridization occurs in a narrow zone in the central Great Plains. Socorro Island form sometimes regarded as a separate species, P. socorroensis (Socorro Towhee) (AOU 1998). See Banks and Browning (1995) for a discussion of nomenclatural issues involving PIPILO.
Conservation Status
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NatureServe Status

Global Status: G5
Global Status Last Reviewed: 09Apr2016
Global Status Last Changed: 04Dec1996
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Reasons: Widespread distribution from British Columbia south to Central America; most trend estimates stable or increasing. Threatened to some degree by clearing of brushy habitat. Two island subspecies extinct as a result of removal of brush by introduced goats.
Nation: United States
National Status: N5 (01May1996)
Nation: Canada
National Status: N5B,N5M (15Jan2018)

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 Arizona (S5), California (SNR), Colorado (S5), Idaho (S4), Kansas (S2B,S3N), Louisiana (S2S3N), Minnesota (SNA), Missouri (SNA), Montana (S5B), Navajo Nation (S5B), Nebraska (SNRB,SNRN), Nevada (S5), New Mexico (S5B,S5N), North Dakota (SNRB), Oregon (S5), South Dakota (S5B), Texas (S4), Utah (S4S5B,S4N), Washington (S5B,S5N), Wyoming (S5B,S5N)
Canada Alberta (S5B), British Columbia (S5), Manitoba (S1S2B), Ontario (SNA), Saskatchewan (S5B)

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: southern British Columbia, southern Alberta, and southern Saskatchewan south to southern California, northwestern Baja California, southern Nevada, Arizona, and through the Mexican highlands to Chiapas and central Guatemala, and east to the central Dakotas, north-central and western Nebraska, central Colorado, eastern New Mexico, and extreme western Texas; disjunctly in southern Baja California (AOU 1983, Greenlaw 1996). See Sauer et al. (2000) for large-scale mapped density estimates (range-wide) based on North American Breeding Bird Survey (BBS) data. NON-BREEDING: south coastal British Columbia, Nevada, Utah, and Colorado (casually farther north) south to Baja California, northern Sonora, through the Mexican breeding range to central Guatemala, and to south-central Texas (AOU 1983).

Number of Occurrences: 81 to >300

Population Size: 10,000 to >1,000,000 individuals

Overall Threat Impact Comments: Vulnerable to land management activities that reduce or remove brushy vegetation, particularly along streamsides, in forest understories, and in dry shrubland habitats. PARASITISM: A frequent host to cowbird brood parasitism; host to Brown-headed Cowbird (MOLOTHRUS ATER) in North America and Bronzed Cowbird (M. AENEUS) in Guatemala. Apparently does not cover or reject cowbird eggs (Ehrlich et al. 1988, Greenlaw 1996). Incidence of parasitism has apparently increased as Brown-headed Cowbird has expanded range and increased in abundance (Greenlaw 1996). Also an occasional host to brood parasitism and egg-dumping by California Quail (CALLIPEPLA CALIFORNICA), but no information is available on rate of occurrence (Greenlaw 1996). PREDATION: Predators include Cooper's (A. COOPERI) and Sharp-shinned Hawks (A. STRIATUS; Reynolds and Meslow 1984, Kennedy and Johnson 1986). Other suspected predators of nests and young include King Snake (LAMPROPELTIS GETULUS), Western Scrub-Jay (APHELOCOMA CALIFORNICA), Striped Skunk (MEPHITIS MEPHITIS), Long-tailed Weasel (MUSTELA FRENATA), California Ground Squirrel (SPERMOPHILUS BEECHEYI), and Western Gray Squirrel (SCIURUS GRISEUS, Greenlaw 1996).

Short-term Trend: Increase of >10%
Short-term Trend Comments: A widespread species that varies greatly in local abundance. BBS trend estimates show long-term stable to increasing populations survey-wide, 1966-1999 (0.6% average annual increase, P = 0.13, N = 618 survey routes) and a significant increase survey-wide between 1980 and 1999 (0.9%, P = 0.02, N = 577). State and province data show significant increases, 1966-1999, in Washington (3.5%, P = 0.00, N = 60), Utah (8.0%, P = 0.04, N = 36), Saskatchewan (5.2%, P = 0.02, N = 15) and British Columbia (1.9%, P = 0.01, N = 47). More recently, significant increases are evident for 1980-1999 in Washington (3.4%, P = 0.00, N = 59), and British Columbia (1.9%, P = 0.03, N = 43). No significant declines evident from the short or long-term trend estimates where sample sizes are large enough for reliable estimates. Mapped trends for 1966-1999 show increasing trends through most of the species' range, with local areas of declining trends along eastern and western range peripheries (Sauer et al. 2000). Two endemic island races, one on Guadalupe Island, Mexico (P. ERYTHROPHTALMUS CONSOBRINUS), and another on San Clemente Island, California are now extinct, both losses due to removal of all shrubby vegetation by domestic goats (Howell and Cade 1953, Jones and Diamond 1976).

Other NatureServe Conservation Status Information

Distribution
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Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDING: southern British Columbia, southern Alberta, and southern Saskatchewan south to southern California, northwestern Baja California, southern Nevada, Arizona, and through the Mexican highlands to Chiapas and central Guatemala, and east to the central Dakotas, north-central and western Nebraska, central Colorado, eastern New Mexico, and extreme western Texas; disjunctly in southern Baja California (AOU 1983, Greenlaw 1996). See Sauer et al. (2000) for large-scale mapped density estimates (range-wide) based on North American Breeding Bird Survey (BBS) data. NON-BREEDING: south coastal British Columbia, Nevada, Utah, and Colorado (casually farther north) south to Baja California, northern Sonora, through the Mexican breeding range to central Guatemala, and to south-central Texas (AOU 1983).

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 AZ, CA, CO, ID, KS, LA, MN, MO, MT, ND, NE, NM, NN, NV, OR, SD, TX, UT, WA, WY
Canada AB, BC, MB, 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; WILDSPACETM 2002


U.S. Distribution by County Help
State County Name (FIPS Code)
ID Ada (16001), Bannock (16005), Cassia (16031), Custer (16037), Gooding (16047), Latah (16057), Lemhi (16059), Oneida (16071), Shoshone (16079)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
16 Curlew Valley (16020309)+
17 Upper Coeur D'alene (17010301)+, Portneuf (17040208)+, Lake Walcott (17040209)+, Raft (17040210)+, Goose (17040211)+, Upper Snake-Rock (17040212)+, Big Lost (17040218)+, Big Wood (17040219)+, Boise-Mores (17050112)+, Middle Salmon-Panther (17060203)+, Lemhi (17060204)+, Clearwater (17060306)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A bird (towhee).
Reproduction Comments: Clutch size usually 3-5 (range 2-6). Will renest if first broods suffer mortality, and second broods are uncommon. Incubation, entirely by female, lasts 12-14 days. Only female broods but both parents feed young and remove fecal sacs. Young leave nest unable to fly at 9-11 days; parents continue to feed dependent young out of nest for another 30 days (Ehrlich et al. 1988, Greenlaw 1996, Baicich and Harrison 1997). A host to brood parasites (see Threats above).
Ecology Comments: In nonbreeding season, forms loose flocks and can be somewhat gregarious. Family groups remain together throughout summer (Ehrlich et al. 1988). See Greenlaw (1996) for density estimates and patterns.
Non-Migrant: Y
Locally Migrant: Y
Long Distance Migrant: Y
Mobility and Migration Comments: Migration patterns variable among different populations. Northern interior breeding populations are migratory or partly migratory; increasingly sedentary southward and near coastal areas. Migratory populations arrive in northern breeding areas in March-April (Terres 1980, Greenlaw 1996). Pacific Coastal birds mostly resident, although some in interior coast are short-distance migrants. In some areas summer residents migrate and are replaced by more northern birds that overwinter (Greenlaw 1996).

Spring arrival in northern parts of range between late March and mid-May; fall departure between early September and early October (Greenlaw 1996). Northern Great Plains populations winter in southwest New Mexico to southeast Texas and Mexico. South-central Rocky Mountain populations winter from Arizona to east-central Texas and Mexico. North Central Rocky Mountain birds winter from southern California to southeast Arizona (Greenlaw 1996).

Palustrine Habitat(s): Riparian
Terrestrial Habitat(s): Shrubland/chaparral, Woodland - Conifer, Woodland - Hardwood, Woodland - Mixed
Habitat Comments: BREEDING: Uses a wide variety of shrubby habitats characterized by deep litter and humus on ground, and sheltering vegetation overhead (Greenlaw 1996). Undergrowth of open woodland, forest edge, second growth, brushy areas, chaparral, riparian thickets, woodland (AOU 1998).

In northern Great Plains, found in shrubby riparian thickets along streams, rivers and coulees, also in woodland undergrowth. In interior mountains and plateaus, uses riparian thickets, open south-facing slopes of ridges, and canyon bottoms. In southern Rocky Mountains, common in pine-oak and pinyon-juniper forests, uncommon in mixed coniferous forests, and rare in ponderosa pine and aspen forests (Hejl et al. 1995). In Colorado pinyon-juniper woodlands, associated with moderately open areas on steep slopes with high shrub cover (Sedgwick 1987). In Pacific Northwest sometimes occurs in shrubby forest successional stages. In California Coast Range, found in chaparral and rose-blackberry thickets (ROSA-RUBRUS; Greenlaw 1996). In Mexico, uses typical brushy woodland and scrub, understory of pine forests and pine-oak woodlands, chaparral, semi-open areas with scattered bushes and brush (Howell and Webb 1995).

Associated with an extensive list of shrubby and thicket-forming plants, including: scrub oaks (QUERCUS spp.), Pinyon Pine (PINUS EDULIS), juniper (JUNIPERUS), yucca (YUCCA spp.), baccharis (BACCHARIS spp.), willow (SALIX spp.), senecio (SENECIO spp.), madrone (ARBUTUS spp.), rose (ROSA spp.), blackberry (RUBUS spp.), saltbush (ATRIPLEX spp.), mountain mahogany (CERCOCARPUS sp.), toyon (HETEROMELES ARBUTIFOLIA), elder (SAMBUCUS spp.), buckthorn (RHAMNUS spp.), sagebrush (ARTEMISIA spp.), snowberry (SYMPHORICARPOS spp.), chamise (ADENOSTOMA spp.), manzanita (ARCTOSTAPHYLOS spp.), sumac (RHUS spp.), Pacific poison-oak (RHUS DIVERSILOBA), ceanothus (CEANOTHUS spp.), and grape (VITIS sp.; Greenlaw 1996). In Mexico, also found in bushy composites (Greenlaw 1996).

Constructs a well-built cup nest in litter on ground, under bush or brush pile, clump of grass, or elevated in vines, trees, bushes, usually between 0.6 and 3.6 m from the ground. Often in relatively exposed conditions, though concealed by nearby plants (Greenlaw 1996; Baicich and Harrison 1997). Elevation of nests may be influenced by rainfall or predation (Greenlaw 1996).

NONBREEDING: Uses similar shrubby habitats and thickets in wintering areas. Nonbreeding birds may occur in areas where towhees do not breed (Greenlaw 1996). In Arizona, winters in Upper Sonoran foothills, in brushy canyons and river valleys of southeastern Arizona, and uncommonly in riparian woodland, willows and marshes along the lower Colorado River (Phillips et al. 1964, Rosenberg et al. 1991).

Adult Food Habits: Frugivore, Granivore, Invertivore, Nectarivore
Immature Food Habits: Frugivore, Granivore, Invertivore, Nectarivore
Food Comments: Forages on the ground beneath shrubs and undergrowth, using a two-footed scratching maneuver to find food among loose debris (Greenlaw 1996). Eats various invertebrates, seeds, small fruits, some small vertebrates (Terres 1980). Diet includes many types of beetles (Coleoptera); grasshoppers and crickets (Orthoptera); true bugs (Heteroptera); ants and wasps (Hymenoptera); flies (Diptera); butterflies and moths, including larvae (Lepidoptera); leafhoppers, aphids and allies (Homoptera); spiders (Araneae); millipedes (Diplopoda); and sowbugs (Isopoda; Greenlaw 1996). Commonly eats seeds and fruits, particularly in nonbreeding season, and sometimes blossoms and young leaves (Dahlsten et al. 1985, Greenlaw 1996). In California, stomach contents (N = 6) were 84.1% animal, 13.2% vegetable and 2.7% mineral (Dahlsten et al. 1985), but relative composition varies with season and locality (Greenlaw 1996). See Greenlaw (1996) for extensive list of plants found in diet. Less known about composition of diet in nonbreeding season, particularly types of invertebrate prey.
Adult Phenology: Diurnal
Immature Phenology: Diurnal
Length: 22 centimeters
Weight: 42 grams
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: A bird of brushy tangles, shrubby streamsides, and forest undergrowth, often in drier shrub habitats than Eastern Towhee. Until recently, considered the same species as Eastern Towhee (P. ERYTHROPHTHALMUS) under the common name Rufous-sided Towhee; both these towhees show a large degree of genetic variation geographically. Can be found in association with human environments where brushy habitats remain, but is vulnerable to brush clearing and to brood parasitism by cowbirds.
Species Impacts: None known. May play a beneficial role by feeding on insects and dispersing seeds of soft fruits.
Preserve Selection & Design Considerations: Most landscape level relationships for this species are unstudied. Area requirements, use of corridors, and relationships to ecological processes such as fire are unknown. Apparently benefit from forest fragmentation that promotes shrub successional stages, at least for a time (Rosenberg and Raphael 1986, Stiles 1980), but fragmentation and loss of shrub habitats would be detrimental. As towhees often use brushy riparian habitats, they may naturally use stream and river courses as corridors.

The genetic variation evident in this species should be a consideration in conservation. As a group the "red-eyed" towhees (P. ERYTHROPHTHALMUS, P. MACULATUS, and P. OCAI) display complex patterns of geographic variation and hybridization. For P. MACULATUS alone, nine subspecies are recognized in western North America north of Mexico, and another twelve are known in Mexico and Guatemala (Greenlaw 1996). In the Great Plains, Spotted Towhee interbreeds with Eastern Towhee, and in Mexico interbreeds with Collared Towhee (P. OCAI). See Greenlaw (1996) for more detail on patterns of hybridization, subspecies variation, and gene flow. Sibley and Sibley (1964, cited in Greenlaw 1996) suggest that in Mexico, hybridization between species may have been promoted by human alterations of landscapes that modified ecological barriers (such as the altitudinal zonation of vegetation) and created new ecotones where species would overlap.

Management Requirements: Management should focus on maintaining shrub and sapling layers in preferred forest and shrub habitats, particularly extensive areas of dense, woody thickets and riparian willows and brush (Greenlaw 1996). Management activities may be beneficial or detrimental, depending on how shrub habitats are affected. Towhees will coexist with humans where landscapes are lightly to moderately altered and shrub habitats remain, but heavy development, urbanization, and land conversion destroy habitat (Greenlaw 1996). The prevalence of domestic cats in residential and rural landscapes may increase mortality of adult birds and nestlings (Greenlaw 1996). Brood parasitism by Brown-headed Cowbirds (MOLOTHRUS ATER) is a particular concern. Cowbirds are likely affecting productivity in some areas, with possible long-term consequences for local populations.

FOREST MANAGEMENT: Towhees will occupy forest interiors, forest edges, riparian areas and shrub successional stages of harvest units, and natural openings wherever brushy growth provides foraging and nesting habitat. Management activities that remove shrub layers (e.g., timber harvest, grazing, or fire) would be detrimental in the immediate term until shrubs return. On the other hand, timber harvest, prescribed fire, and wildfire that eventually promote shrub growth or increase the area of favored shrub habitats would be beneficial for the time shrub successional habitats remain. Thus management impacts should be analyzed in a context of habitat patterns across landscapes and cumulative effects. Unfortunately, quantitative information on towhee relationships to management activities and ensuing habitat changes is slim.

In Washington, Stiles (1980) found towhees present in early successional stages of Red Alder (ALNUS RUBRA) up to 12 m in height, but absent in older stands with taller alder. In California valley-foothill hardwood, valley-foothill hardwood-conifer, and valley-foothill riparian habitats towhees are associated with shrub understory of sapling age classes with sparse canopy and 10-24% closure (USFS 1994). In California fragmented Douglas-fir (PSEUDOTSUGA MENZIESII) forests, towhees were associated with recent clearcuts and showed significant positive correlations with percent clearcut, total edge, and insularity (degree to which remaining forest stands were surrounded by clearcuts; Rosenberg and Raphael 1986). However, in a Giant Sequoia (SEQUOIA GIGANTEUM) forest, they disappeared from plots where the living and deadwood understory was removed by cutting and prescribed burning (Kilgore 1971). In Colorado pinyon-juniper woodlands, found in natural openings and chained sites where the tree overstory had been removed and shrubs remained. Positively associated with distance to a habitat edge and with shrub height, but negatively associated with tree canopy height and richness of grass and forb species (Sedgwick 1987).

GRAZING: There is little quantitative information available on grazing effects; response would depend on grazing intensity, timing, and subsequent changes to shrubby vegetation. Also of concern, however, is that towhees are frequent cowbird hosts. Cowbirds are attracted by the presence of livestock and cowbird brood parasitism impacts on host bird productivity can be substantial. Thus towhee presence and vegetation structure by themselves are inadequate in determining livestock effects and productivity must be monitored. Cowbird parasitism rates may also be affected and compounded by landscape patterns at different spatial scales (Tewksbury et al. 1999), but this is unstudied in relationship to this species.

Showed a positive response to grazing in aspen (Page et al. 1978, cited in Saab et al. 1995). Sedgwick and Knopf (1987) found that moderate late-fall grazing of cottonwood bottomland plots in northeastern Colorado did not affect densities in the short term (three years). Densities did vary in parallel from year to year in the control and treatment plots.

However, a comparison of grazed and ungrazed pinyon-juniper with oak understory in New Mexico showed that abundance levels are deceptive in determining the effects of grazing. In the first two years of the study, towhees were more abundant in "ungrazed" plots that had been rested from grazing for 20 years than in moderately grazed plots (three-season grazing November-June with 1.3 ha per animal unit month), but no difference was found in abundance in the second two years. However, nest success was lower in grazed plots. Towhees in grazed plots suffered nest failure from weather and brood parasitism by cowbirds (which are attracted by the presence of livestock), whereas birds in the ungrazed plots did not. Twenty-six percent of nests (n = 23) in grazed plots were parasitized. Nest predation rates were the same in the two treatments. Interestingly, the authors found no differences between means of vegetative measures in grazed and ungrazed plots (Goguen and Mathews 1998).

Monitoring Requirements: A diurnal bird with a distinctive song, can be readily detected by point count and other standard monitoring techniques. Randomized sample of regional bird surveys may not adequately sample shrub and riparian habitats, reducing detection rates in some areas. The song varies regionally. Pacific coast birds sing a simple trill of variable speed; interior birds give introductory notes, then a trill (NGS 1999). Catlike "mew" call is variable but distinctive, often made while scolding or mobbing (Greenlaw 1996). See Davis (1957) for information on aging birds by plumage in hand.
Management Research Needs: Quantitative information is needed on relationships to habitat types, vegetation structure, landscape patterns, and vegetation change over time. Very little information available on the effects of land management activities, and further study is needed of current forest management practices, effects of different grazing regimes in different habitats, and habitat loss to land conversion at local and regional scales. Information needed on rates of brood parasitism and effects on productivity and populations, particularly in relation to landscape patterns. Also need information on rates of predation on eggs and young. Landscape relationships, use of corridors, area and patch size requirements, seasonal movements, and all aspects of ecology during migration and nonbreeding season need further study.
Biological Research Needs: There have been few quantitative studies on the species, the existing studies mostly coming from the Pacific Coast and Mexico, and our knowledge comes largely from anecdotal information (Greenlaw 1996). More information is needed on basic biology and description, genetics, breeding biology, territoriality and territory size, site fidelity, behavior, demography, phenology, migration patterns and pathways, wintering areas, and general ecology. Geographic variation among subspecies and patterns of hybridization need to be studied with genetic methods (Greenlaw 1996).
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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Management Information Edition Date: 20Dec2000
Management Information Edition Author: C. PAIGE
Management Information Acknowledgments: Funding for the preparation of this abstract was provided by the Department of Defense, Partners in Flight Program, through The Nature Conservancy, Wings of the Americas Program.
Element Ecology & Life History Edition Date: 20Dec2000
Element Ecology & Life History Author(s): PAIGE, C., AND G. HAMMERSON, REVISIONS BY S. CANNINGS

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

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