Survey reveals 44% decline in rare Tricolored Blackbirds Findings show steep drop in California species that was already of great concern to conservationists.
By Jerry Ting, Published: Jun 18, 2014 San Francisco, CA – For more information, or if you need photographs or video, please call Daniela Ogden at (415) 644-4606.
A comprehensive survey of Tricolored Blackbirds in California has confirmed that the population of the rare species has declined 44 percent since 2011. The 2014 survey – led by UC Davis, in partnership with Audubon California, California Department of Fish and Wildlife, and the U.S. Fish & Wildlife Service — counted 145,000 Tricolored Blackbirds, down from 260,000 in 2011.
The Tricolored Blackbird, which once numbered in the millions, lives almost entirely in California, and has long been of concern to conservationists. Habitat loss and breeding colony disruption are considered to be the main causes of its decline.
“It’s disheartening to witness this bird struggling to survive in California,” said Monica Iglecia, conservation project director with Audubon California. “This year’s drought reduced the amount of wetland habitat in the spring and summer, which is when Tricolored Blackbirds are nesting and when they need it most. This presents a serious danger for a population this small.”
The 2014 survey was completed with the help of more than 143 volunteers. Surveys were conducted at 801 sites across 41 counties. Members from several Audubon chapters took part.
The survey confirmed that Tricolored Blackbirds continue to reside primarily in the southern portion of the Central Valley but that number is rapidly decreasing. Their numbers also plummeted in Kern and Merced counties. Only six birds were found in Fresno County, and no birds were observed in Kings, Santa Clara or Sonoma counties. Relatively greater percentages of the birds were seen in Amador, El Dorado and Sacramento counties than in recent surveys.
“It’s California’s blackbird,” said UC Davis staff researcher Robert Meese, who led the survey. “If we as Californians don’t care about the species, we can’t rely on any other state to come in and bail us out. It’s our responsibility because it’s our bird.”
Tricolored Blackbirds historically nested in vast wetlands of the Central Valley, but for decades the birds have established large nesting colonies in triticale, the plant that dairymen feed their cows. Unfortunately, harvest season coincides with the birds’ nesting season. When these fields are harvested before young birds have fledged, thousands of eggs and nestlings are lost.
In recent years, Audubon California has partnered with the Natural Resources Conservation Service and the U.S. Fish & Wildlife Service to strike agreements with farmers to delay harvests to allow the young birds to fledge. These agreements with dairy farmers have saved many thousands of blackbirds.
“Results from the survey show a disturbing trend and reinforce the need for quick conservation action from a range of partners in California to stem the Tricolored Blackbird’s decline,” said Robert H. Doster, with U.S. Fish & Wildlife Service.