|
|
Common Loon migration, western Turkey Vultures, and Black Oystercatchers on an Alaska islandBirding Briefs -- August 2005
Published: June 24, 2005 Loon Sightings Answer Migration Questions
Eight years ago, biologist Darwin Long scooped a female Common Loon from a mountain lake in northwestern Montana.
He snipped a feather, took a blood sample, weighed and measured the bird, and hoped his work would shed light on questions raised by his bosses at the Maine-based Biodiversity Research Institute. They were studying how toxins in the food chain were affecting loons, how youngsters disperse, where loons go in winter, how long it takes to get there, and by what route they travel. He had no idea how important that night's work would be.
Last Christmas, Long was working in Morro Bay, on the California coast, studying loons in their Pacific winter range, when he spotted a familiar leg tag. Sure enough, it was COLO 938-260-50, the same bird he dipped out of Montana's Lower Stillwater Lake eight years before.
Long tracked the loon through the winter with help from the Morro Coast Audubon Society. It is the only banded loon ever tracked from Montana to the Pacific, and he wanted to know when it would return north. The bird left on March 27.
Long fired e-mails to Montana, and a small army of volunteers watched for the loon's arrival. It showed up on Lower Stillwater on March 31, making the 950-mile trip in about five days, faster than anyone had expected. It was, he says, "a first for the West."
The timing, Long said, hints at the route, indicating that the bird came overland rather than up the coast. But five days also points to the loon making several stops along the way. Pinpoint those stops, he says, and you can begin to map out places where conservation efforts should be focused. He plans to track the bird back to the ocean come fall and perhaps to outfit it with a transmitting device before it heads north again.
"We aren't done with this bird yet," Long says. "She still has so much to teach us." -- Michael Jamison
|
Drought May Account for Fewer Turkey Vultures
The Turkey Vulture began to expand its range northward as early as the 1920s. Proof that the expansion has continued in the last quarter--century appeared in the August 2003 issue of the Condor, the journal of the Cooper Ornithological Society.
Breeding Bird Surveys, Christmas Bird Counts, and raptor passage counts had pointed to significant increases in western states from 1977 to 1998, but hawkwatches and Christmas counts noted fewer vultures from 1998 to 2001, coinciding with the onset of the West's severe drought.
The paper's authors, Stephen W. Hoffman of the Pennsylvania Audubon Society and Jeff P. Smith of Hawkwatch International, report that mortality of most western vultures and raptors may have increased due to the drought, but birds also may have shifted their migration routes toward the Pacific coast, where the drought was not as severe, bypassing the study's count sites.
In addition, the Turkey Vulture's northward expansion "might reflect the positive response of a tropical species to global warming," the authors write. Other probable factors include logging, rural development, ranching, and hunting, all of which have made it easier for vultures to find such carrion as road-killed wildlife, dead livestock, and dead game animals.
And vultures are not picky about their choice of nesting sites. They nest in farmland, woodland, pastures, lakeshores, and rocky cliffs. Within those habitats, the birds use large cavities in hollow or broken tree tops, caves, hay lofts in old barns, rooms in abandoned houses, and enclosed tree stands erected by deer hunters. When all else fails, Turkey Vultures may nest on the ground, situating their nests so they abut with a tree trunk or fallen log. -- Carrol Henderson
|
Oystercatchers Thrive on Earthquake-Altered Island
On March 27, 1964, a magnitude 9.2 earthquake struck Alaska, causing landslides, avalanches, and a tsunami and killing 130 people. It was the second largest earthquake ever recorded.
The quake uplifted portions of the mainland, as well as several islands. Middleton Island, located in the Gulf of Alaska about 65 miles south of the entrance to Prince William Sound, rose as much as 13 feet, creating an extensive, intertidal lowland area that now surrounds the entire island.
The changed topography reduced the number of cliff-nesting seabirds on Middleton, but the new lowlands have become home to a growing colony of Black Oystercatchers. The birds were first recorded on the island in 1976, when a single pair nested. Five years later, three pairs nested, and in the 1990s, the population increased rapidly. At last count, in 2002, 718 birds, including 171 pairs, occurred on Middleton, representing seven percent of the world population of the species.
Federal biologists Verena Gill, Scott Hatch, and Richard Lanctot report in the November 2004 issue of the Condor that the intertidal zone was initially unfavorable for oystercatchers, but as the habitat improved, the birds moved in. Low predation levels and little human disturbance have led to a high level of nesting success.
|
This Just In
Predators killed two Whooping Cranes in May after the endangered birds had completed their spring migrations to Wisconsin. The losses brought to seven the number of cranes from the eastern reintroductory project that have died in the last year, leaving 43 birds. To prevent future deaths, project leaders may develop more rigorous predator avoidance training.
Blue-throated Macaws have been found in Bolivia more than 60 miles west of previous records, according to World Birdwatch magazine. The wild population of the critically endangered parrot, which was profiled in the April issue of Birder's World ("Too Pretty," p.26), is believed to be fewer than 250 individuals. Researchers counted 12 macaws in western Beni province, and they estimate that as many as 25 inhabit the region.
The Northern Spotted Owl population has declined since 1994, despite an 80 percent reduction in logging in the Northwest, according to a federal report. Scientists had expected an annual owl decline of about 3.1 percent until enough habitat grew to stabilize populations. The actual decline has been steeper -- including an average of 7.1 percent in four areas in Washington. Learn more about the study here.
A team sponsored by Birder's World and Bushnell Sports Optics took third place in the youth division at this year's World Series of Birding in New Jersey. The Bird Bounties team of high-schoolers Dave DiCianni, Erik Enbody, and Caroline Womer counted 180 species on May 14. The event, sponsored by New Jersey Audubon, drew 1,000 participants and raised more than $600,000 for bird-conservation projects. |
|
Not a registered member? It's free to sign up.
See great photos of birds, get birdwatching tips, learn about birding events, and more!
|