Tricolored Blackbird

Agelaius tricolor

(c) Robert Meese
  • ICTERIDAE
  • Blackbirds, Orioles, and allies
  • Icteridae
  • Tordo Tricolor
  • Carouge de Californie
Introduction

The Tricolored Blackbird breeds in dense colonies throughout the Central Valley and some coastal regions of California. Research suggests that its population has declined dramatically in apparent response to habitat loss. Although the Tricolored Blackbird looks similar to the ubiquitous Red-winged Blackbird and is closely related, the two species are genetically, behaviorally, and morphologically distinct.

Appearance Description

This species closely resembles the Red-winged Blackbird, with subtle differences in coloration and shape. The adult male is black with a glossy bluish tint in sunlight. Its wing coverts or epaulets are dark red and whitish. The Red-winged Blackbird's epaulets are lighter red to orange and buffy white to yellow (never pure white). The immature male resembles the adult, but with duller black and gray plumage. Darker than the female Red-winged Blackbird, the adult female Tricolored is blackish overall and streaked with gray. Her light grey chin and throat are also streaked. The wings and bill of Tricolored Blackbird are longer and narrower than the Red-winged Blackbird's. Weighing 2.1 ounces on average, this songbird measures about 8.75 inches with a 14-inch wingspan.

Range Map
Courtesy Kenn Kaufman
Range Distribution

More than 99% of Tricolored Blackbirds live in 46 of California's 58 counties, and most of the largest colonies have historically occurred in the Sacramento and San Joaquin Valleys. The range extends to the western foothills of the Sierra Nevada and Coast Ranges, and some coastal areas of northern and southern California. They also breed at scattered and isolated locations in Oregon, Washington, western Nevada, and northern Baja California. When not breeding, Tricolored Blackbirds flock along the central California coast and in the Sacramento and San Joaquin River Delta.

Habitat

In the 1930s, the vast majority of Tricolored Blackbird colonies were in freshwater marshes dominated by cattails or bulrushes. By the 1970s, this tendency had dramatically changed; only about half of observed colonies were in such marshes, with others in upland or agricultural areas especially fields farmed for grain and silage. Colonies also use stands of blackberries, giant cane, tamarisk, and river-bottom trees like willow and cottonwood. Natural grasslands, dairy farms, cattle feedlots, rangeland, seasonal pools, and hay fields are used for foraging. Tricolors tend to roost in cattail marshes.

Feeding

Tricolored Blackbirds forage mostly on the ground but occasionally chase insects into the air. Inserting their bills into leaves, soil, or jumbles of small rocks, sticks, or fallen vegetation, the blackbirds opens their bills to create a gap. The diet shifts as new food sources become available. Many insects are consumed: the larvae of flies, butterflies, moths, and dragonflies; agricultural pests like weevils; beetles; grasshoppers; and midges. Emergent plants and seeds are seasonally important: agricultural grains (cracked corn, oats, barley, and the sprouts of rice) and weed seeds. Hatchlings start with an insect diet, but can eat seeds within two weeks.

Reproduction

In late winter, male Tricolored Blackbirds begin to sing, then move into nesting areas in early spring. Flocks of males sing in a loud chorus and fly together in order to establish a colony, which sometimes displaces other blackbird species, like the Red-winged. With song and ritualized displays, individual males usually establish territories before the females arrive. A typical display features lowered and spread wings and tail, an arched neck, and ruffled neck feathers. One to four females, most often one, make a small territory within the male's larger territory. A male that attracts more than one nesting female at the same time is considered polygynous. Courtship displays and ritualized nest selection bond a pair.

Attached to standing vegetation or thin tree branches, the female weaves a cup nest of stems and leaves. For about 12 days, she incubates 3-4 pale blue or green eggs, marked with browns, purples, or black. The male evacuates the colony, only to return shortly after the chicks emerge practically naked and blind. In about a week, fledglings leave the nest to form creches. Adults encourage flight and eventually lead the young flock to form a group in an adjacent marsh. Females may produce a second brood, but often change locations to do so.

Migration

At the extremes of its breeding range, populations in northern California, Oregon, Washington, and Baja California leave the breeding grounds in winter and move into central California, but many California birds only make seasonal movements within the state.

CBC Graph
Graph Legend
Annual Population Indices
  • 247,500
  • 247,500
Population Status Trends

Accounts from the 1800s describe large colonies and winter flocks from the Central Valley to southern California. A systematic population survey published in 1937 estimated more than 700,000 adult birds per year between 1931 and 1936 in only eight counties in the Central Valley. A survey conducted in the Central Valley between 1969 and 1972 reported an average of about 133,000 individuals per year. Two statewide surveys of similar scope and effort, performed by the same investigators, indicate a decline from 370,000 breeding adults in 1994 to about 233,000 in 1997, with declines most apparent in the Central Valley. The decline continued through 2000, when the population was estimated at 162,000 individuals. Since then, the numbers have apparently stabilized.

Conservation Issues

The Tricolored Blackbird seems to be suffering the same fate as other troubled colonial nesters, including extinct ones, like the Carolina Parakeet. Its shrinking population is concentrated in a few viable colonies, which are threatened by further habitat loss. In September 2004, the California Department of Fish and Game denied a petition by the Center for Biological Diversity to list this blackbird as Endangered, but agreed that "action may be warranted." The U.S. Fish and Wildlife Service and California list it as a Species of Concern. Citing a small and declining population, restricted distribution, and recognizable threats, BirdLife International considers this songbird Endangered (2007).

The main threats to the Tricolored Blackbird are the loss of breeding habitat to agriculture and urban development, conflicts with agricultural practices, increased nest predation (especially by locally increasing Great-tailed Grackles), and a lack of public concern for a species that can appear common because it flocks. In 1850, the Central Valley, host to the largest blackbird colonies, had 13 million acres of fresh water wetlands. These wetlands were reduced to 795,000 acres in by 1939 and then 544,000 acres by 1985. During this period, the Tricolored Blackbird decreased by over 50%. It adapted to wetland destruction by breeding and foraging on farmland, especially silage and dairy farms. Entire colonies were subsequently lost, as recently as the 1990s, when crops were harvested and fields were plowed.

To secure the current population, a 2004 report for the California Partners in Flight recommended: continued surveys of known and potential colonies; active management of remnant freshwater marshes; more outreach and support for farmers; development of alternative habitats for colonies on dairy and silage farms; and the support and expansion of colonies in urban environments, in order to increase public awareness. Recently, Audubon California and the U.S. Fish and Wildlife Service have been working with farmers to compensate them for delayed haying to allow young blackbirds to fledge from their nests. In the 2007 breeding seasons, cooperating farmers spared approximately 50,000 Tricolored Blackbird nests.

What You Can Do

Audubon's Important Bird Area (IBA) program is a vital tool for the conservation of the Tricolored Blackbird.  You can find this songbird at the Merced National Wildlife Refuge (8 miles south of Merced, CA), support the U.S. refuge system, and explore an IBA all in one visit.

Support local land trusts, government agencies, and other organizations working in wetland habitats in your area. Contact your Important Bird Areas coordinator to find out if there are sites in your area important for Tricolored Blackbirds that need increased protection. Volunteers are crucial to the success of programs that monitor the long-term status of Tricolored Blackbirds. Audubon's Christmas Bird Count (CBC) is one of the longest-running citizen-science monitoring programs in the world and has helped to follow changes in the Tricolored Blackbird's numbers and distribution. Learn more about the CBC and how you can participate. 

Find out about actions you can take including Audubon programs and activities.

More Information

Learn more about this species and other birds through these resources

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Natural History References

Beedy, E. C., and W. J. Hamilton III. 1999. Tricolored Blackbird (Agelaius tricolor). In The Birds of North America, No. 423 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.

Sibley, David Allen. 2000. The Sibley Guide to Birds. Alfred A. Knopf, New York.

Conservation Status References

Beedy, E. C., and W. J. Hamilton III. 1999. Tricolored Blackbird (Agelaius tricolor). In The Birds of North America, No. 423 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.

BirdLife International (2007) Species factsheet: Agelaius tricolor. Compiled by Stuart Butchart et al. Accessed 7 July 2007. 

Frayer, W. E., Dennis D. Peters, and H. Ross Pywell. Wetlands of the California Central Valley: Status and Trends 1939 to mid-1980's. U. S. Wildlife Service, Region 1, Portland Oregon, June 1989. 28 pages.

Gustafson, J. R., and D. T. Steele. 2004 (Sep 15.). Evaluation of petition from Center
for Biological Diversity to list Tricolored Blackbird (Agelaius tricolor) as endangered.
Calif. Dep. of Fish and Game, Habitat Conservation Planning Branch, Sacramento, 42
pp. + append.

Hamilton, W. J. 2004. Tricolored Blackbird (Agelaius tricolor). In The Riparian Bird Conservation Plan:a strategy for reversing the decline of riparian-associated birds in California. California Partners in Flight. Accessed 1 July 2007.