The Rusty Blackbird is in serious trouble

Male Rusty Blackbird

Researchers are becoming increasingly concerned that the population of Rusty Blackbirds is plummeting and they're not certain why. They're asking birders to help count the migrating birds so they can obtain a clearer picture of what's wrong.

The Cornell Lab of Ornithology calls the Rusty Blackbird "one of North America's most rapidly declining species." Formerly abundant, the population has plunged by at least 85 percent over the past 40 years.



The Rusty Blackbird is a medium-sized blackbird with a slender bill and a medium-length tail. In winter, the male is distinguished by its rusty brown feather edges, pale yellow eye and buffy eyebrow. The female is gray-brown. It also has rusty feather edges, pale eyes and a bold eyebrow, contrasting with darker feathers right around the eye.

The bird is a bit larger and longer-tailed than the Red-winged Blackbird (with its brilliant red wing patch) and a shorter tail and slimmer bill than the Common Grackle. It shares the pale yellow eye of the grackle. If you listen closely to the sounds of a large blackbird flock, you may hear their song: a gurgling, creaky sound like a rusty-hinged gate being opened.

Female Rusty Blackbird

Rusty Blackbirds are ecologically distant from other blackbirds. You won't see them at a backyard feeder. In the summer breeding season in northern Canada, they are found in boreal wetlands. Winter will find them in wooded wetlands in eastern and southeastern United States.

The birds have been seen in the Lehigh Valley this autumn and winter. The Eastern PA Birdline, a project of the Lehigh Valley Audubon Society, reported sightings at 11 different locations this season, especially in Upper Mount Bethel Township, Northampton County. The first sightings came on September 25, 2013; the latest occurred during the week of February 28. Most leave the Lehigh Valley by late April.

Researchers have been investigating the causes of the population decline. They've found that Rusty Blackbirds in their breeding grounds have mercury concentrations three to four times than those found elsewhere. The feathers give one indication: Mercury levels return to normal in the winter but soar during breeding season in Canada. The mercury harms breeding, leaving fewer fledglings. Other possible explanations include changes in logging, agricultural practices, loss of habitat in wintering grounds and wetlands drying due to climate change.

Researchers this week began asking you to report birds in your woods and wetlands. Cornell ornithologists have partnered with other organizations to coordinate a Rusty Blackbird Migration Blitz—a continent-wide effort to track Rusty Blackbirds.

To learn more about this project and find out how you can contribute your sightings, go to the International Rusty Blackbird Working Group at www.rustyblackbird.org. Make sure you hurry, though. The Rusty Blackbird migration in the Lehigh Valley is drawing to a close.