viernes, 31 de enero de 2014

Influx of Snowy Owls Thrills and Baffles Birders

Launch media viewer Norman Smith, who runs the Snowy Owl Project for Mass Audubon, released a female snowy owl on a beach in Duxbury, Mass. Gretchen Ertl for The New York Times

DUXBURY, Mass. — The snowy owl seemed almost complacent, showing the confidence of a top predator whose bright yellow eyes suggested she might be sizing you up as a weaker combatant — or perhaps a large snack.

She had been where no bird should safely be — Logan International Airport in Boston — and now, regal and imposing even in brief captivity, she represented the latest of her kind to arrive in a remarkable and growing winter’s wandering to the Lower 48.

Not only is the Boston area seeing the largest number of snowy owls ever recorded, they are popping up in territory far from their usual habitat near the Arctic Circle. Ecstatic bird watchers have spotted them perched atop the Chesapeake Bay Bridge and in Washington (where one made headlines for being struck by a bus) , in Little Rock, Ark., and northern Florida — even in Bermuda.

This year’s been bizarre,” said Dan Haas, a birder in Maryland. “The numbers have been unprecedented. Historic.
 Related Coverage

The Lede: Tracking the Snowy Owl Migration in Real TimeDEC. 19, 2013

No one is sure why so many snowies are showing up in so many places — whether it can be attributed to more food in their Arctic habitats than usual, or climate change at the top of the world. Think about the canary in the coal mine,” said Henry Tepper, the president of Mass Audubon, “you think about the snowy owl in the Arctic.
Launch media viewer Patrick Castleberry, left, took photos of a snowy owl at Little Talbot Island State Park in Jacksonville, Fla. The very rare sighting of the owl in the area drew birders from miles around. Will Dickey/Florida Times-Union, via Associated Press

The big birds known as Bubo scandiacus reach a height of 20 to 27 inches and have a wingspan of 54 to 66 inches
. They can live more than 30 years in captivity, and have feathers that can range from mottled brown and white to pure white. They have their own movie star – Harry Potter’s Hedwig — and Internet meme, the image of a snowy asking the impertinent question “O RLY?” as in “Oh, really?”

It’s such a charismatic bird,” said David Sibley, the author and illustrator of a series of birding guides.

Sighting one, especially in an unexpected place, can be thrilling for birders. Georgeta Pourchot was apparently the first person to identify the Florida owl. She and her husband, Eric, were driving in late December from their home in Virginia through Florida on their Christmas vacation when she suggested they pull off at Little Talbot Island, near Jacksonville, to look for unusual birds: snow buntings, she thought, or a long-billed curlew.

Ms. Pourchot said as birders, she and her husband are “just beginners.” They scanned two beaches without seeing anything interesting. They encountered a park ranger, who suggested they look a little farther: “When you get to the other side of that ‘Do Not Enter’ sign, there’s a good view over there.

So they drove past the sign and parked. And as she got out of the car, Ms. Pourchot told her husband, “Babe, I think we have a snowy owl here!”

You’re kidding,” he replied, but acknowledged that while they might have been looking for the avian equivalent of a zebra, they had happened on a unicorn.

On Dec. 27, she posted her report to ebird, an online tracking system created by Cornell University’s department of ornithology and the National Audubon Society. The next day, members of the local Audubon chapter were doing their annual Christmas bird count when word spread, said Kevin E. Dailey, the leader of one team. The news was so exciting that volunteers left their assigned zones in search of the truly rare bird. “That’s kind of heresy to leave your count circle area,” he said.

Some people are less happy to encounter snowy owls — particularly, the managers of airports that the birds are drawn to. With wide open spaces and short grass, “the airports, to them, look more like the Arctic tundra than anything else,” said Norman Smith, who runs the Snowy Owl Project for Mass Audubon. The Port Authority of New York and New Jersey took heated criticism in December when it shot three snowy owls. Since then, the authority has tried trapping the birds, with limited success, and harassing them away from the airport by shooting off fireworks, said Ron Marsico, a spokesman for the Port Authority.

Mr. Smith had trapped the female owl at Logan one recent morning and had driven her here to the beach at Duxbury, about 40 miles southeast, for release into the wild, with hopes that she would continue heading south, away from the airport. In most years, Mr. Smith makes a trip from Logan to Duxbury or other release sites a half-dozen times. This year, however, the number has climbed above 75. “And the season is only half over,” he said.

When he released his grip on the owl’s legs, the bird flapped her broad wings and headed to the southwest, toward a small cluster of homes. Suddenly, another snowy owl sailed down from the houses and met the newcomer in midair, their talons locking. An aerial territorial skirmish followed as the two wheeled overhead, with the newcomer finally heading off to the west.

Ornithologists and bird watchers are not sure why the birds have come so far and in such great numbers this year. In decades of study, Mr. Smith said, “what I’ve learned is we know very little about this bird.” He suggests that the large population is the result of a bonanza of lemmings and other small rodents that snowy owls feed on, perhaps a consequence of the milder Arctic weather. That led to larger population of hatchlings that must spread farther and farther out to find territory of their own.

The lemming hypothesis does not satisfy Kevin J. McGowan, an ornithologist at Cornell. He noted that tiny transmitters placed on the owls have shown some of the birds do a surprising thing in winter: Instead of flying to the more temperate south, they fly farther north and scout the Arctic ice pack for pools of open water populated by sea ducks and other waterfowl.

Climate change
, which has been thawing Arctic ice so actively that new shipping routes are opening in the far north, could have disrupted the habitat,
Professor McGowan speculated. “That has to be one of the most vulnerable ecosystems on the planet. That’s going to be one of the first places that falls apart when there is warming in the atmosphere,” he said. This may have driven more of them south instead of north. A big shift in bird movement one year might just be a freak event, he said, or potentially “it’s the beginning of a pattern.

Whatever the reason for their abundance, the snowy visitors have brought attention beyond the usual core group of birders, said Mr. Sibley, the guide author. Mr. Sibley, who has released a print of one of his snowy owl illustrations to raise money for research, said that while it is good to see such excitement, “it would be great if that kind of attention could extend to less flashy birds, like the red cockaded woodpecker or the Henslow’s sparrow.

JAN. 31, 2014

No hay comentarios:

Publicar un comentario

Nota: solo los miembros de este blog pueden publicar comentarios.