FAIRBANKS - The reason behind the dramatic decline in rusty blackbirds is a gray area. Scientists don’t know why the population of “rusties,” as they are affectionately called by bird watchers, has declined by nearly 90 percent nationwide over the past few decades. The rapid decline has earned the birds a place on the Red List of the Alaska WatchList, which lists vulnerable or declining bird species in the state.
The possible causes of the decline range from loss of forest wetlands on their wintering grounds in the Midwest and southeastern United States, to shifts in boreal wetlands due to climate change, to exposure to harmful chemicals. The current population estimate of rusty blackbirds in the U.S. is somewhere around 2 million.
One reason little is known about the birds in Alaska is because they’re hard to find. Rusty blackbirds nest in the boreal forest throughout the Interior and across Canada. They are northernmost-nesting blackbird species on the continent. The birds nest in bogs, muskegs, and along streams, feeding on aquatic insects.
“They’re a pain in the butt to study because of the habitat they live in,” April Harding Scurr, one of the researchers who has conducted studies in Alaska, said. “It’s always in wetlands. It’s boggy, tussocky, mosquitoey, stinky mud.”
Rusty blackbirds, which are about the size of a robin, get their name from the rusty feather tips they have on the head, breast and back, though most of the rusty color has worn off by spring and the birds that arrive in Alaska, especially males, appear all black. The birds also have distinctive pale, yellow eyes that stand out even in flight.
Although they are songbirds, most people probably wouldn’t call the song pretty — it sounds like a rusty gate hinge — but each spring the birds can be heard throughout the boreal wetlands in Alaska and Canada.
Citizen science project
In an attempt to learn more about rusty blackbirds and the reason behind their steep decline, bird researchers in Alaska and the Lower 48, collectively called the International Rusty Blackbird Working Group (IRBWG), have initiated a citizen science project called the Rusty Blackbird Spring Migration Blitz.
The goal of the project is to help document the timing and location of the birds’ migration routes from their wintering grounds in the southcentral and southeastern United States to their summer nesting grounds in the boreal wetlands of Alaska and Canada.
During the Blitz, volunteer observers across North America are being asked to report sightings of rusty blackbirds in an online database called eBird to help track where and when the blackbirds migrate. Audubon Alaska and the Alaska Department of Fish and Game are coordinating the effort in Alaska. The observation period in Alaska started April 12 and ends May 31.
“We’re recruiting an army of birders and bird enthusiasts to participate in this effort to help conserve this disappearing bird,” said Dave Tessler, a biologist for the Alaska Department of Fish and Game in Anchorage and a member of the IRBWG. “Starting observations this early in migration season in Alaska will help document first arrivals of rusty blackbirds within the state.”
The first rusty blackbirds of the season were reported in Fairbanks last week, about a week later than normal.
The current status of rusty blackbirds in Alaska is somewhat a mystery because there are no good historical records for the species, mainly because the breeding areas aren’t really covered by standard surveys, according to Steve Matsuoka, a wildlife biologist with the U.S. Fish and Wildlife Service in Anchorage. There’s no question the number of birds in Alaska has declined but beyond that not much is known.
“A lot of what we know about the decline is because of citizen science,” Matsuoka says.
In addition to citizen science, there have been a number of research projects in Alaska conducted by the U.S. Fish and Wildlife Service, the Alaska Department of Fish and Gameand the now-defunct Alaska Bird Observatory to learn more about rusty blackbirds. Study sites include the Tanana Flats, the Yukon Flats, Cordova and near Anchorage.
Tessler participated in some of the first rusty blackbird studies in Alaska. Overall, the survival rate of rusty blackbird chicks here is comparable to other songbirds, he said, as are adult survival and the number of chicks that fledge.
In Alaska, adults are relatively faithful to the general areas where they nest, Tessler said.
“About a 6 or 7 on a scale of 10,” he said.
Thanks to a 2009–2010 study by Matsuoka, Tessler and others, researchers are starting to learn where at least Anchorage-area rusty blackbirds go when they leave the state. By attaching small devices called geolocators, which record length and timing of daylight to determine latitude and longitude, the study revealed the route the migrating blackbirds took.
The Anchorage-area birds flew down through northern Alberta and then Saskatchewan, continuing to North and South Dakota, following the Central Flyway migration route that runs roughly between the Mississippi River and the Rocky Mountains in the U.S. The trip south was leisurely, taking more than two months. On the way north in spring, the blackbirds were in more of a hurry, taking nearly the same route in reverse over the course of two weeks to a month. This year the research team will deploy more geolocators to find out if individual birds return to the same wintering grounds or if they wander from year to year.
Less is known about the migratory habits of younger birds. Harding Scurr, who is now the science director of the Alaska Songbird Institute in Fairbanks, banded 90 rusty blackbird chicks on the Yukon Flats for a project for her Master’s degree and found only three returning birds over two years. It isn’t clear whether that is due to the young birds simply dispersing or not surviving their first winter.
One of biggest concerns in the birds’ boreal breeding grounds such as Alaska is how changes in climate will affect wetlands. A recent study by University of Alaska Fairbanks researchers showed there was a decrease in the amount of water in wetlands on wildlife refuges across Alaska. It’s unclear how much of an effect these changes have had or will have on rusty blackbirds.
Beth Peluso is communications manager for Audubon Alaska and is currently based in Fairbanks. Contact her at email@example.com.