CENTER SEEKS TO PROTECT THE TRICOLORED BLACKBIRD, NORTH AMERICA’S MOST COLONIAL LANDBIRD
Colonial nesting birds are particularly susceptible to extinction. Three recent North American bird extinctions – the Passenger Pigeon, Carolina Parakeet, and Great Auk – were of colonial or highly social breeders. Because a small number of colonies may contain a high proportion of the population, human impacts can have devastating results.
A BREATHTAKING NATURAL WONDER…..
The Tricolored Blackbird currently forms the largest colonies of any North American landbird, with a single breeding colony often consisting of tens of thousands of birds. In the 1800s, one observer described wintering flocks as darkening the sky “for some distance by their masses.” Once numbering in the millions, the Tricolor population is plummeting at an alarming rate. 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. Without immediate intervention, California may lose one of its most breathtaking natural wonders.
The Tricolored Blackbird breeds in dense colonies in California’s Central Valley, Coast Ranges, and southern California. California supports more than 99% of the population. 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, whereas Red-wings forage within larger breeding territories. Original habitat for the Tricolor 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 Tricolor has been destroyed or degraded, possibly contributing to historical population declines.
Following the widespread loss of native marshes and grasslands, many of the few remaining large Tricolor colonies have taken to nesting in dairy silage fields. Every year, thousands Tricolor nests – most containing eggs or even young nestlings – are mowed down during silage harvest. This wholesale destruction of such a large number of Tricolor nests is threatening the very survival of the species.
Other prime nesting locations, such as blackberry thickets, are lost to land conversions to vineyards, orchards, and urban development, and predation is rampant in the little remaining marsh habitat. 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 censuses provide a clear and unequivocal assessment of a serious population decline over the past century, with a particularly dramatic drop during the 1990s.
THE CENTER TAKES ACTION
In April 2004, the Center submitted a
petition requesting immediate action to
prohibit or delay harvesting and plowing activities on private
lands used by Tricolors during the nesting season. The Center
also pointed out that 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. Both the California Fish
and Game Commission and the U.S. Fish and Wildlife Service
neglected to list the Tricolor on an emergency basis, but
agreed to review the listing petition on a regular timeline.
The Center will continue to push for endangered species status for the Tricolor, and is deeply committed to saving this unique California treasure from the same tragic fate as the Passenger Pigeon.