Center for Biological Diversity

Protecting endangered species and wild places through
science, policy, education, and environmental law.


Center for Biological Diversity Calls for Emergency Protection for the Tricolored Blackbird

Contact: Monica Bond, Center for Biological Diversity (909) 659-6053 x304, (909) 961-7720 cell
Julie Teel, Center for Biological Diversity (909) 659-6053 x308
More Information: Petition

Idyllwild, CA — The Center for Biological Diversity (“Center”) called on government wildlife agencies to grant emergency protection for the Tricolored Blackbird (Agelaius tricolor), a bird native to California that scientists say has experienced a precipitous decline in the past decade. California supports more than 99% of the Tricolor population.

The Tricolored Blackbird forms the largest colonies of any North American passerine (passerines make up 3/5 of all living birds in the world), and one breeding colony may consist of thousands of birds. While the sheer size of some individual colonies can make the species appear abundant, the overall population has declined dramatically over the past 70 years. Once numbering in the millions, the Tricolor population is plummeting in California at an alarming rate in large part due to the harvest of silage and plowing of weedy fields on dairy farms in the Central Valley.

Every year, thousands of pairs of blackbirds – comprising some of few remaining large colonies – unsuccessfully nest on some agricultural lands because their eggs and nests are destroyed during silage harvest. “This wholesale destruction of such a large number of Tricolor nests is threatening the very survival of the species,” stated Monica Bond, a biologist with the Center. “It would be a travesty to let this unique bird suffer the same fate as the Passenger Pigeon, another formerly abundant colonial species that no one ever imagined could be driven to extinction.”

The Center submitted a petition requesting immediate action by the U.S. Fish and Wildlife Service (“FWS”) and California Department of Fish & Game (“DFG”) prohibiting or at a minimum delaying harvesting and plowing activities on private lands used for breeding during the nesting season. These activities are in clear violation of the federal Migratory Bird Treaty Act and California’s Unfair Competition Law and are responsible for the current precipitous decline of the species that necessitates immediate listing under the state and federal Endangered Species Acts.

“This decline will only be reversed if DFG, FWS, and citizen enforcers ensure private parties comply with the governing laws,” said Center attorney Julie Teel. “The agencies have known about the problem for decades, yet no meaningful protection for the blackbird has yet been afforded.”

Tricolors also experience widespread habitat losses to land conversions from rangeland to vineyards, orchards, and urban development, and high levels of predation in the little remaining marsh habitats.


The Tricolored Blackbird breeds in dense colonies largely in California’s Central Valley, Coast Ranges, and southern California. The species looks similar to the Red-winged Blackbird but is behaviorally different; the Tricolor defends very small breeding territories within a colony and forages outside the colony, sometimes up to four miles away. Original habitat for the species consisted of extensive freshwater emergent marshes and native grasslands that once covered the Central Valley and other parts of California. Most of the prime native habitat for the blackbird has been destroyed or degraded, possibly contributing to historical population declines. However, the species has demonstrated remarkable flexibility in utilizing non-native habitats such as thickets of Himalayan blackberry and grain silage fields. Unfortunately, these nesting habitats are now disappearing rapidly due to urbanization and crop harvest during the Tricolor breeding season.

Beginning in the 1930s and continuing until 2000, five extensive population censuses were conducted to estimate population size of the Tricolored Blackbird. A 1975 study concluded that the population of Tricolors in the Central Valley had declined by at least 50% compared to the 1930s. Three censuses in the 1990s found that the Tricolor population had continued to decline; numbers of birds fell by about 37% between 1994 and 1997 and by an additional 38% between 1997 and 2000. These studies provide a clear and unequivocal assessment of a serious population decline over the past century, with a particularly dramatic drop during the 1990s.

To obtain a copy of the petition, contact Monica Bond at

The Center for Biological Diversity (“the Center”) is a non-profit, public interest environmental organization dedicated to the protection of native species and their habitats through science, policy, and environmental law. The Center has over 9,000 members throughout California and the United States.


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