Far-flying Sooty Shearwaters, Ivory-bill DNA, summer rarities, bird flu tests, and bird-safe windows
Birding Briefs -- December 2006
Published: October 20, 2006
|Ocean-going Sooty Shearwater Migrates Farther than All Birds|
Move over, Arctic Tern. Another bird is in fact the world's longest-distance avian migrant.
New research shows that the Sooty Shearwater, an abundant, falcon-size seabird, migrates an average of 39,800 miles a year in a figure-eight pattern across the entire Pacific Ocean. The flight is about 37 percent farther than the tern's migration between Arctic regions and the Antarctic pack ice.
Biologist Scott Shaffer of the University of California Santa Cruz and his colleagues placed electronic tracking tags on the legs of 33 shearwaters at two New Zealand breeding colonies in early 2005 and recovered working tags from 19 of the birds later that year. The data from the tags painted a detailed picture of each bird's daily activities.
Shearwaters flew up to 565 miles each day and foraged for fish, squid, and krill from the ocean's surface to as deep as 225 feet. After leaving New Zealand in early April, a few birds traveled to the coast of Chile, site of another shear¬water breeding colony. All birds soon moved north to one of three wintering areas - off the coasts of Japan, Alaska, and California. No birds moved between the wintering areas, and on their return trip, all crossed the equator through a relatively narrow 1,240-mile corridor in a 10-day span in October.
The research was described in the Proceedings of the National Academy of Sciences and is available at www.toppcensus.org.
|Ivory-bill May Be Two Distinct Species|
Even though scientists do not have a live Ivory-billed Woodpecker and its larger Mexican cousin, the Imperial Woodpecker, to study, they're still answering questions about the iconic birds. The latest questions to be addressed: How closely are the North American and Cuban Ivory-bill subspecies related to each other and to the Imperial? And how did Ivory-bills arrive in Cuba?
In a paper published last summer in Biology Letters, researchers led by Robert C. Fleischer, head of the genetics program at the Smithsonian Institution, found that the two Ivory-bills and the Imperial "are roughly equidistant genetically, suggesting each lineage may be a separate species." His team tested DNA from small skin samples from the toes of 13 woodpecker specimens - seven North American Ivory-bills, three Cuban Ivory-bills, and three Imperials. DNA analysis showed that the three birds became mitochondrially distinct about one million years ago.
Cuba's Ivory-bills, the researchers say, probably moved to the island from the Yucatan Peninsula when sea levels were much lower than they are today, making a water crossing by forest-dwelling woodpeckers conceivable.
The research has spurred American Ornithologists' Union scientists to take up the question of whether or not to split the Cuban and North American Ivory-bills into separate species. Stay tuned.
|15,000 Birds Tested, No Bird Flu Found|
After months of government-sponsored monitoring this year in the United States and Canada, involving the testing of more than 15,000 birds, not one wild migratory bird has been found carrying the worrisome highly pathogenic avian influenza H5N1 virus.
The low-pathogenic form of the virus was found in two Mute Swans in Michigan and in Mallards in Maryland and Pennsylvania. Low-pathogenic H5N1 is not a health hazard to people and causes at most mild sickness in birds. (See http://wildlifedisease.nbii.gov/ai/ for the latest on bird flu surveillance.)
The lack of highly pathogenic H5N1 in wild birds shores up the views of Smithsonian Institution ornithologist John Rappole and others who dispute the conventional belief that migratory birds are spreading the virus. Rappole suggests in the October issue of Emerging Infectious Diseases that migratory birds are unlikely to introduce the deadly virus to North America. He says the role migratory birds play in spreading the virus in the Eastern Hemisphere is unclear, and he points to the historical lack of exchange of avian influenza viruses between the Eastern and Western Hemispheres.
Instead, the more likely source of highly pathogenic H5N1 into North America, says Rappole, will be the legal or illegal import of an infected bird. "Control of legal and illegal imports should be the primary focus of prevention efforts," he writes.
|Freedom Tower Windows Planned with Birds in Mind|
The 1,776-foot Freedom Tower that is being built on the site of the World Trade Center in New York City will feature window glass intended to minimize collisions by birds. The textured glass, which is still being developed, will use prisms to "look as solid as stone to a bird," says Jeffrey Holmes of the architecture firm Skidmore, Owings, and Merrill. The New York City Audubon Society pushed for bird safety to be an element of the building's design. - Meera Subramanian
Rare Visitor from Afar
Photo by © Mark Bartosik
It was a summer of spectacular rare birds. A Western Reef-Heron, a species from the Eastern Hemisphere, drew birders to a Nova Scotia lake June 26-August 2. Presumably the same bird was found two weeks later in Maine and New Hampshire. The sighting was only the third ever in North America. Birds from Central and South America also got our attention. A Southern Lapwing was found at Florida's St. Marks National Wildlife Refuge in May, and a lapwing was photographed in Maryland in June. A Yellow Grosbeak and at least seven Aztec Thrushes were in Arizona. And two Northern Jacanas visited the Lower Rio Grande Valley, including the one pictured above.