Endangered Tricolored Blackbird Protected in California

10 December 2015 | Center for Biological Diversity News Release

SAN DIEGO— Acting on a petition from the Center for Biological Diversity, the California Fish and Game Commission voted today to advance tricolored blackbirds as a candidate species under the California Endangered Species Act. Candidate species receive all the protections of a listed species for a year while the commission and staff make a final status determination. Tricolored blackbirds have declined by nearly 90 percent since the 1930s; today’s decision is the result of four attempts by the Center to gain protection for the imperiled birds.

“There’s no question that tricolored blackbirds desperately need this long-overdue protection to avoid their slide toward extinction,” said Ileene Anderson, a senior scientist with the Center. “The California Fish and Game Commission made the right decision, based on the overwhelming science documenting the ongoing population declines of these birds.”

Tricolored blackbirds — which once formed massive nesting colonies of millions of birds in California’s Central Valley — have declined dramatically due to destruction of wetlands and native grasslands, shooting, pesticide use and mass destruction of nests through mowing and harvest of crops tricoloreds use for nesting. Comprehensive statewide surveys found only 395,000 tricoloreds in 2008, followed by a decline to 259,000 in 2011 and only 145,000 in 2014 — the smallest population ever recorded.

The Center first petitioned for emergency protection for tricoloreds in 2004. The Fish and Game Commission rejected the petition, ignoring the recommendation of experts familiar with the species. After a decade of further population declines, the Center petitioned again for emergency listing in October 2014, and the commission implemented emergency protections from nest destruction and shooting, but those protections expired in June 2015. Finally, today, the commission recognized the dire need for protection for this species and voted 3-1 to advance the tricolored blackbird as a candidate under the California Endangered Species Act list, providing immediate protection for the birds for the next year until a final decision is reached.

Background

The tricolored blackbird (Agelaius tricolor) breeds in dense colonies in California’s Central Valley, coast ranges and Southern California. More than 99 percent of tricolors live in California; the primary breeding range is the Sacramento and San Joaquin valleys. Adult males are a glossy blue-black with striking red-and-white shoulder patches, while females are mostly black with a small, reddish shoulder patch. Tricolored blackbirds typically eat insects but also eat grains, snails and small clams.

Tricoloreds form the largest breeding colonies of any North American land bird, with a single colony often consisting of tens of thousands of birds, as a defense against predation. In the 1800s one observer described a wintering tricolored flock in Solano County as “numbering so many thousands as to darken the sky for some distance by their masses,” and in the 1930s a biologist reported a flock of more than a million tricoloreds in the Sacramento Valley. Tricolored numbers declined in the Central Valley by at least 50 percent between the 1930s and early 1970s, and an additional loss of more than half of the remaining population was reported from 1994 to 2000.

Forced from their natural nesting sites by conversion of wetlands and native grasslands to urban and agricultural development, many tricoloreds have adapted by nesting in agricultural crops — typically dairy silage fields. Harvest of these crops often coincides with egg laying and hatching, and many tricolor eggs and nests are destroyed during harvests. Recent surveys documented nearly half of the entire tricolored population nesting in just two colonies in the Central Valley in dairy silage fields in which thousands of nests containing eggs and hatchlings were mowed down during harvest. An unknown number of tricoloreds are shot each year by rice farmers to protect their crops.

The California Department of Fish and Wildlife and other partners have attempted voluntary measures to save tricolor nests from destruction during crop harvest by making crop purchases or reimbursing farmers for delayed harvest on private agricultural lands where tricolors nest. But these efforts have not stopped the decline of the species or prevented destruction of tricolor nests on many dairy farms. For example, in 2011, more than half of all tricolor nests in silage fields were destroyed despite efforts to contact farmers and coordinate buyouts or harvest delays.

Contact: Ileene Anderson, (323) 490-0223, ianderson@biologicaldiversity.org


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