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Success for Snowy Plovers, nest-destroying cows, hope for Red Knots, and two new grouseBirding Briefs -- October 2006
Published: August 25, 2006 Snowy Plovers Nest Successfully Off the Beach
Along the Pacific coast, the primary nesting areas for the threatened Western Snowy Plover are beaches, and beaches hosting plovers are actively managed to keep people and predators away. (And with success, as you can read on page 29.)
But this doesn't mean that the birds won't nest away from beaches - or in largely unmanaged habitat.
Biologist Mark Colwell of Humboldt State University and colleagues report in the Journal of Field Ornithology that plovers are nesting successfully on gravel bars along nine miles of the lower Eel River, about 20 miles south of Eureka, in Northern California.
River-nesting birds, he writes, are almost twice as likely to produce young as beach-nesting birds. But after three years in which more plovers nested on the river than on beaches, the pattern is now reversed: More than 60 percent of plovers began nesting on beaches in 2004.
To improve the success rates of the birds' beach nests, Colwell believes more management techniques, such as hazing with slingshots and removal of ravens and crows that prey on plover chicks, are required. |
Check-list Changes Make Two Grouse out of Blue Grouse
The American Ornithologists' Union has determined that the Blue Grouse, a mostly gray bird of western forests, is actually two species: Dusky Grouse and Sooty Grouse.
The AOU's Committee on Classification and Nomenclature announced the split - along with other changes and sweeping reclassifications of tribes and subfamilies - in the 47th supplement to the Check-list of North American Birds. The supplement was published in the July 2006 issue of the society's journal, the Auk, and is available online at www.aou.org.
Two other splits were made: Cape Verde Shearwater from Cory's Shear¬water and Barbados Bullfinch from Lesser Antillean Bullfinch.
Most of the changes announced in the supplement reflect new understandings of the relationships of species provided by cutting-edge DNA research. The woodcreeper family was merged with ovenbirds. The skuas and jaegers, previously considered a subfamily within the family of the gulls and terns (Laridae), were elevated to the status of family (Stercorariidae). And the genus Asturina was merged into Buteo, restoring to the Gray Hawk the scientific name it had had until 1998: Buteo nitidus.
Of the 17 terns in the genus Sterna, 13 were reclassified in five new genera. Willet and Gray-tailed and Wandering Tattlers were moved to the shorebird genus Tringa. And six West Indian cuckoos joined six other species in the genus Coccyzus.
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Nest-Wrecking Cows Caught on Tape
White-tailed deer, red deer, caribou, and sheep have all been documented as predators of bird nests. Now we can consider another plant-eating mammal a nest wrecker: the cow.
In the summers of 2000 and 2001, Jamie Nack, a wildlife outreach specialist with the University of Wisconsin, used remote cameras to monitor 54 nests of grassland birds in actively grazed pastures in southwestern Wisconsin. Disturbance by cows caused 14 nests to fail.
Nack expected to capture footage of the bovines inadvertently trampling or laying on the occasional nest but was surprised to see cows using their mouths to remove eggs and nestlings.
The animals took three of four Savannah Sparrow eggs from one nest, four Eastern Meadowlark nestlings from a second, and three Savannah Sparrow nestlings from a third. She also discovered dead nestlings and missing eggs. Although Nack can't say for certain that the cows consumed the nests' contents, she can say the animals caused the nests to fail. Her report appeared in the March 2005 issue of the Wilson Bulletin.
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This Just In
A major East Coast stopover site for migratory Red Knots has been saved from development and put off-limits to commercial horseshoe-crab harvesters. The Conservation Fund, an environmental group, announced in May that it had purchased 73 acres of Mispillion Harbor in Delaware. Reportedly, 80 percent of the knots that visit Delaware Bay each spring feed and rest in the harbor.
The number of Trumpeter Swans jumped 47 percent from 2000 to 2005, according to a new U.S. Fish and Wildlife Service report. Surveyors estimated a total population of 34,803 swans, up from 23,647 five years ago. Young birds accounted for 28 percent of the latest tally.
Laysan Ducks bred successfully at Hawaii's Midway Atoll National Wildlife Refuge for the second straight year, federal scientists say. The endangered ducks were translocated from Laysan Atoll in October 2004 and 2005. At last count, the population on Midway was 48 adults, including 10 hens sitting on eggs and 19 ducklings. The birds are the rarest native waterfowl in the United States.
Thousands of egrets, herons, and other birds disappeared from a rookery at Lake Martin in Louisiana last spring. The reason is unknown, but habitat changes caused by last year's hurricanes may be to blame.
On the heels of seabird die-offs along the Pacific coast from California to British Columbia comes more troubles for ocean-dependent species. Biologists at the Farallon Islands west of San Francisco reported in July that virtually all 20,000 Cassin's Auklet nests on the islands will fail for the second straight year and that most Common Murre nests will not fledge chicks.
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