Agelaius tricolor - (Audubon, 1837)
Tricolored Blackbird
Other English Common Names: tricolored blackbird
Taxonomic Status: Accepted
Related ITIS Name(s): Agelaius tricolor (Audubon, 1837) (TSN 179060)
French Common Names: Carouge de Californie
Spanish Common Names: Tordo Tricolor
Unique Identifier: ELEMENT_GLOBAL.2.101015
Element Code: ABPBXB0020
Informal Taxonomy: Animals, Vertebrates - Birds - Perching Birds
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Aves Passeriformes Icteridae Agelaius
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: Agelaius tricolor
Taxonomic Comments: A. phoeniceus a sister taxon (AOU 1998).
Conservation Status
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NatureServe Status

Global Status: G1G2
Global Status Last Reviewed: 25Apr2014
Global Status Last Changed: 25Apr2014
Ranking Methodology Used: Ranked by calculator
Rounded Global Status: G1 - Critically Imperiled
Reasons: Nests in colonies primarily in California; historically more numerous than at present; now relatively stable, but vulnerable to localized habitat loss and degradation from agricultural practices, urbanization, or inappropriate water management, and vulnerable to reduced reproductive success from impacts of native predators.
Nation: United States
National Status: N3N4 (28May2013)

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 California (S1S2), Nevada (S1B), Oregon (S2B)

Other Statuses

IUCN Red List Category: EN - Endangered

NatureServe Global Conservation Status Factors

Range Extent: 20,000-200,000 square km (about 8000-80,000 square miles)
Range Extent Comments: Breeding range extends from central southern Oregon south through interior California, and along the coast from central California south to localized areas in northwestern Baja California. Abundance is highest in central and central northern California (Breeding Buird Survey data); most of the largest colonies are in the Central Valley (Beedy and Hamilton 1999). During the nonbreeding period the range contracts somewhat as the species withdraws from several areas around the margins of the breeding range (Beedy and Hamilton 1999).

Area of Occupancy: 126-500 4-km2 grid cells
Area of Occupancy Comments: Nesting area of occupancy encompasses at least 200 grid cells measuring 2 km x 2 km.

Number of Occurrences: 81 - 300
Number of Occurrences Comments: This species is represented by a large number of nesting colonies, but most individuals may be concentrated in a very few. For example, in the 1990s, 60 percent were concentrated in the ten largest colonies (Hamilton et al. 1995; Beedy and Hamilton 1997; Hamilton 2000). Additionally, many individuals may concentrate into relatively few winter roosts.

Population Size: 100,000 - 1,000,000 individuals
Population Size Comments: Total adult population size in the mid-2000s was approximately 260,000 (Tricolored Blackbird Working Group 2007).

Number of Occurrences with Good Viability/Integrity: Some (13-40)
Viability/Integrity Comments: In April 2004, statewide California surveys focused on only those colonies that had supported more than 2,000 adults in at least one previous year. Of 184 sites surveyed, only 33 supported active colonies at the time of the survey (Green and Edson 2004). Of the 33, 13 held more than 2,000 adults each, collectively representing >96% of the census total (Beedy 2008).

Overall Threat Impact: High - medium
Overall Threat Impact Comments: The species has undergone a long-term population decline, primarily due to losses and fragmentation of breeding and foraging habitats caused by urban and agricultural land conversions, and water diversions (Tricolored Blackbird Working Group 2007). Most of California's formerly extensive freshwater wetlands have been lost, and the remaining ones often are small isolated patches that support high densities of predators (e.g., coyote, raccoon, black-crowned night-heron, common raven; great-tailed grackle in southern California), which sometimes may cause significant reductions in blackbird reproductive success through predation or disturbance (Tricolored Blackbird Working Group 2007).

Inappropriate water management sometimes causes nesting failures if managed water levels are too shallow (not deep enough to deter raccoon and other predators) or too deep (flooding nests, such as has occurred at Lake Isabella) (Tricolored Blackbird Working Group 2007).

Losses of formerly productive foraging habitats (especially those within 5-6 kilometers of breeding colony sites) to perennial, woody crops (primarily almonds and grapes) and to urbanization are serious threats (Tricolored Blackbird Working Group 2007). In addition, untimely harvesting of silage grains in locations where colonies have settled causes complete breeding failure of many thousands of birds for at least one breeding attempt (Cook and Toft 2005).

Concentration of a high proportion of the population in a few breeding colonies increases the risk of major reproductive failures, especially in vulnerable habsuch as active agricultural fields (Beedy 2008)..

Despite localized threats to habitat and from predators, USFWS (2006) concluded that these factors do not represent significant threats to the continued existence of the species. USFWS (2006) also found that contaminants and other factors do not pose significant threats.

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend Comments: Trend over the past 10 years or three generations is uncertain but probably relatively stable. Range-wide Breeding Bird Survey (BBS) data indicate an average annual increase of 2.9 percent (95% CI = -0.2, 5.2) for 1966-2011 and 3.3 percent (95% CI = -2.5, 8.0) for 2001-2011. During 1966-2011, most of the range in central and southern California had an increasing trend, whereas a decreasing trend was evident north of central California and in a portion of central California (BBS data). However, the BBS methodology is regarded as not adequate for monitoring tricolored blackbird population size and distribution (see Beedy 2008).

California statewide totals of adults in four late-April surveys covering all recently known colony sites were: 369,359 (1994); 237,928 (1997); 104,786 (1999); and 162,508 (2000). A statewide census in 2005 indicated a California population of approximately 260,000 (Tricolored Blackbird Working Group 2007)..

Long-term Trend: Decline of 30-70%
Long-term Trend Comments: Overall range of the species has changed little since the mid-1930s, but breeding no longer occurs in some historical locations (e.g., parts of northwestern Baja California), and in some areas formerly large populations are now much smaller (Beedy and Hamilton 1999). Overall population is greatly reduced from that observed by Neff (1937) during the 1930s (Tricolored Blackbird Working Group 2007).

Other NatureServe Conservation Status Information

Inventory Needs: Need continued inventory of breeding colonies and nonbreeding roosts, particularly the largest ones where most individuals may occur.

Protection Needs: Additional protection of nonbreeding roosts may be warranted.

Distribution
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Global Range: (20,000-200,000 square km (about 8000-80,000 square miles)) Breeding range extends from central southern Oregon south through interior California, and along the coast from central California south to localized areas in northwestern Baja California. Abundance is highest in central and central northern California (Breeding Buird Survey data); most of the largest colonies are in the Central Valley (Beedy and Hamilton 1999). During the nonbreeding period the range contracts somewhat as the species withdraws from several areas around the margins of the breeding range (Beedy and Hamilton 1999).

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 CA, NV, OR

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)
CA Alameda (06001), Amador (06005), Butte (06007), Calaveras (06009), Colusa (06011), Contra Costa (06013), El Dorado (06017), Fresno (06019), Glenn (06021), Humboldt (06023), Kern (06029), Kings (06031), Lake (06033), Lassen (06035), Los Angeles (06037), Madera (06039), Marin (06041), Mendocino (06045), Merced (06047), Modoc (06049), Monterey (06053), Napa (06055), Orange (06059), Placer (06061), Riverside (06065), Sacramento (06067), San Benito (06069), San Bernardino (06071), San Diego (06073), San Joaquin (06077), San Luis Obispo (06079), Santa Barbara (06083), Santa Clara (06085), Santa Cruz (06087), Shasta (06089), Siskiyou (06093), Solano (06095), Sonoma (06097), Stanislaus (06099), Sutter (06101), Tehama (06103), Tulare (06107), Tuolumne (06109), Ventura (06111), Yolo (06113), Yuba (06115)
NV Douglas (32005), Washoe (32031)*
OR Jackson (41029)*, Klamath (41035), Multnomah (41051)*, Umatilla (41059)*, Wheeler (41069)*
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
16 Truckee (16050102)+*, Upper Carson (16050201)+
17 Umatilla (17070103)+*, Lower John Day (17070204)+*, Lower Willamette (17090012)+*, Upper Rogue (17100307)+*, Middle Rogue (17100308)+*
18 Lower Eel (18010105)+, Big-Navarro-Garcia (18010108)+, Gualala-Salmon (18010109)+*, Russian (18010110)+, Williamson (18010201)+, Upper Klamath Lake (18010203)+, Lost (18010204)+, Upper Pit (18020002)+, Lower Pit (18020003)+, Mccloud (18020004)+*, Sacramento-Stone Corral (18020104)+, Lower American (18020111)+, Upper Stony (18020115)+, Upper Cache (18020116)+, North Fork Feather (18020121)+*, Upper Yuba (18020125)+*, Upper Bear (18020126)+, South Fork American (18020129)+*, Cow Creek (18020151)+, Cottonwood Creek (18020152)+, Clear Creek-Sacramento River (18020154)+, Paynes Creek-Sacramento River (18020155)+, Thomes Creek-Sacramento River (18020156)+, Big Chico Creek-Sacramento River (18020157)+, Butte Creek (18020158)+, Honcut Headwaters-Lower Feather (18020159)+, Upper Coon-Upper Auburn (18020161)+, Upper Putah (18020162)+, Lower Sacramento (18020163)+, South Fork Kern (18030002)+, Middle Kern-Upper Tehachapi- (18030003)+, Upper Poso (18030004)+, Upper Deer-Upper White (18030005)+, Upper Tule (18030006)+, Upper Kaweah (18030007)+, Upper Dry (18030009)+, Tulare-Buena Vista Lakes (18030012)+, Middle San Joaquin-Lower (18040001)+, Middle San Joaquin-Lower (18040002)+, San Joaquin Delta (18040003)+, Upper Chowchilla-Upper Fresno (18040007)+, Upper Merced (18040008)+, Upper Tuolumne (18040009)+, Upper Stanislaus (18040010)+, Upper Calaveras (18040011)+, Upper Mokelumne (18040012)+, Upper Cosumnes (18040013)+, Panoche-San Luis Reservoir (18040014)+, Rock Creek-French Camp Slough (18040051)+, Suisun Bay (18050001)+, San Pablo Bay (18050002)+, Coyote (18050003)+, San Francisco Bay (18050004)+, Tomales-Drake Bays (18050005)+, San Lorenzo-Soquel (18060001)+, Pajaro (18060002)+, Carrizo Plain (18060003)+, Estrella (18060004)+, Salinas (18060005)+, Central Coastal (18060006)+, Cuyama (18060007)+, Santa Maria (18060008)+, San Antonio (18060009)+*, Santa Ynez (18060010)+, Alisal-Elkhorn Sloughs (18060011)+, Carmel (18060012)+, Santa Barbara Coastal (18060013)+*, Ventura (18070101)+, Santa Clara (18070102)+, Calleguas (18070103)+*, Santa Monica Bay (18070104)+, Los Angeles (18070105)+, San Gabriel (18070106)+, Seal Beach (18070201)+, San Jacinto (18070202)+, Santa Ana (18070203)+, Newport Bay (18070204)+, Aliso-San Onofre (18070301)+, Santa Margarita (18070302)+, San Luis Rey-Escondido (18070303)+, San Diego (18070304)+, Cottonwood-Tijuana (18070305)+, Honey-Eagle Lakes (18080003)+, Antelope-Fremont Valleys (18090206)+, Mojave (18090208)+, Carrizo Creek (18100202)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A small bird (blackbird).
General Description: Males are black with red, white-tipped shoulder patches (tips are buffy-white in fresh fall plumage); females are sooty-brown and streaked, with varying amounts of red on the shoulders (NGS 1983).
Diagnostic Characteristics: Males differ from male red-winged blackbirds by having a darker red shoulder patch with a white or buffy-white border (buff-yellow or absent in redwing); females are much darker than most races of the redwing and differ from first-year male redwings in lacking a large red shoulder patch; also, females have a bill that is thicker at the base and more sharply pointed (Peterson 1990).
Reproduction Comments: Nesting occurs in April-June. Males defend small territories within colonies and mate with 1-4 females. Clutch size is 3-4. Incubation, by female, lasts about 11 days (Terres 1980). Both parents feed young. Young leave nest 13 days after hatching. Two broods/year. Nests in large colonies (up to thousands of individuals). These blackbirds are itinerant breeders; they may nest more than once at different locations during a single breeding season (Beedy and Hamilton 1999). They often change nesting locations from year to year. Hamilton et al. 1995) found that 19 of 72 colonies (1991-1994) were active the following year (Hamilton et al. 1995). Of 75 colonies active in 1997, 19 were within 500 meters of colonies active in 1994 (Beedy and Hamilton 1997).
Ecology Comments: These birds are highly gregarious. They roost and forage in flocks (Beedy and Hamilton 1999).
Non-Migrant: Y
Locally Migrant: Y
Long Distance Migrant: N
Mobility and Migration Comments: Generally this species withdraws from the northern tip of the breeding range for winter.

Foraging occurs in flocks that range widely to more than 15 kilometers from the nesting colony (Beedy and Hamilton 1999).

Palustrine Habitat(s): HERBACEOUS WETLAND
Terrestrial Habitat(s): Cropland/hedgerow, Grassland/herbaceous
Habitat Comments: Breeding habitat includes freshwater marshes of cattails, tule, bulrushes, and sedges (AOU 1983). Nests are in vegetation of marshes or thickets, sometimes on the ground. Historically this species was strongly tied to emergent marshes; in recent decades much nesting has shifted to non-native vegetation (e.g., Himalayan blackberry). In migration and winter these blackbirds inhabit open cultivated lands and pastures as well as marshes (AOU 1983).
Adult Food Habits: Granivore, Invertivore
Immature Food Habits: Granivore, Invertivore
Food Comments: Insects (e.g., beetles, caterpillars) comprise a large portion of the diet. Diet includes seeds and grain in fall and winter.
Adult Phenology: Diurnal
Immature Phenology: Diurnal
Colonial Breeder: Y
Length: 22 centimeters
Weight: 68 grams
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: Primary conservation priorities for habitat conservation and management are to: (1) maintain, enhance, and protect existing habitat suitable for nesting, foraging, and wintering activities; (2) create and restore additional protected breeding habitats to support nesting and foraging; (3) identify mechanisms for protecting nesting and foraging habitats; (4) to the extent allowable by law, survey private lands and identify largest and most vulnerable colonies; (5) encourage private landowners to protect active breeding colonies; and (6) encourage and enhance active breeding colonies on public lands (Tricolored Blackbird Working Group 2007).

Range-wide population monitoring should be conducted at least once every three years (Beedy 2008).

Better information is needed on the effects of non-native plant species and livestock grazing on tricolored blackbird habitat.

Biological Research Needs: Need to determine most effective non-lethal control methods for times when species is considered an agricultural pest.
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: 28May2013
NatureServe Conservation Status Factors Author: Hammerson, G., D. Mehlman, and S. Cannings
Element Ecology & Life History Edition Date: 27May2013
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
  • 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/.

  • Balda, R. P., and G. C. Bateman. 1971. Flocking and annual cycle of the piņon jay, Gymnorhinus cyanocephalus. Condor 73:287-302.

  • Beedy, E. C. 2008. Tricolored blackbird (Agelaius tricolor). Pages 437-443 in Shuford, W. D., and T. Gardali, editors. California bird species of special concern: a ranked assessment of species, subspecies, and distinct populations of birds of immediate conservation concern in California. Studies of Western Birds 1. Western Field Ornithologists, Camarillo, California, and California Department of Fish and Game, Sacramento.

  • Beedy, E. C. and W. J. Hamilton, III. 1999. Tricolored blackbird (Agelaius tricolor), The Birds of North America Online (A. Poole, editor). Ithaca: Cornell Lab of Ornithology.

  • Beedy, E. C., and W. J. Hamilton III. 1997. Tricolored Blackbird status update and management guidelines. September. (Jones and Stokes Associates, Inc. 97-099) Sacramento, CA. Prepared for U.S. Fish and Wildlife Service, Portland, Oregon, and California Department of Fish and Game, Sacramento, California.

  • Bent, A.C. 1958. Life histories of North American blackbirds, orioles, tanagers, and their allies. U.S. National Museum Bulletin 211. Washington, DC.

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

  • Cook, L. F., and C.A. Toft. 2005. Dynamics of extinction: population decline in the colonially nesting tricolored blackbird Agelaius tricolor. Bird Conservation International 15: 73-88.

  • Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1988. The birder's handbook: a field guide to the natural history of North American birds. Simon and Shuster, Inc., New York. xxx + 785 pp.

  • Green, M., and L. Edson. 2004. The 2004 tricolored blackbird April survey. Central Valley Bird Club Bull. 7:23-31.

  • Hamilton, W. J., III, L. Cook, and R. Grey. 1995. Tricolored Blackbird project 1994. Unpubl. report prepared for U.S. Fish and Wildlife Service, Portland, Oregon.

  • Hamilton, W. J., III. 2000. Tricolored blackbird 2000 survey and population analysis. Unpublished report prepared for U.S. Fish and Wildlife Service, Portland, OR.

  • Horn, H. S. 1968. The adaptive significance of colonial nesting in the Brewer's Blackbird. Ecology 49:682-694.

  • Ligon, J. D. 1971. Late summer-autumnal breeding of the piņon jay in New Mexico. Condor 73:147-153.

  • Moore, W. S., and R. A. Dolbeer. 1989. The use of banding recovery data to estimate dispersal rates and gene flow in avian species: case studies in the Red-winged Blackbird and Common Grackle. Condor 91:242-253.

  • National Geographic Society (NGS). 1983. Field guide to the birds of North America. National Geographic Society, Washington, DC.

  • Neff, J. A. 1937. Nesting distribution of the tri-colored red-wing. Condor 39 (2): 61-81.

  • Orians, G. H. 1980. Some adaptations of marsh-nesting blackbirds. Princeton Univ. Press. 295 pp.

  • Orians, G. H. 1985. Blackbirds of the Americas. Univ. Washington Press, Seattle.

  • Parker III, T. A., D. F. Stotz, and J. W. Fitzpatrick. 1996. Ecological and distributional databases for neotropical birds. The University of Chicago Press, Chicago.

  • Peterson, R. T. 1990b. A field guide to western birds. Third edition. Houghton Mifflin Co., Boston. 432 pp.

  • Poole, A. F. and F. B. Gill. 1992. The birds of North America. The American Ornithologists' Union, Washington, D.C. and The Academy of Natural Sciences, Philadelphia, PA.

  • Sauer, J. R., J. E. Hines, and J. Fallon. 2003. The North American Breeding Bird Survey, results and analysis 1966 - 2002. Version 2003.1, USGS Patuxent Wildlife Reseach Center, Laurel, MD Available at: http://www.mbr-pwrc.usgs.gov/bbs/bbs.html.

  • Small, A. 1994. California birds: their status and distribution. Ibis Publishing Co., 3420 Freda's Hill Road, Vista, California 92084. xiv + 342 pp.

  • Tarvin, K. A., and G. E. Woolfenden. 1999. Blue Jay (Cyanocitta cristata). No. 469 IN A. Poole and F. Gill, editors. The birds of North America. The Birds of North America, Inc., Philadelphia, PA. 32pp.

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