Hurricane Sandy blows migrating birds off track
Hurricane Sandy's winds were so strong that they knocked various seabirds off their migratory courses and sent them along the mainland US.
Mon, Nov 05, 2012 at 03:06 PM
Gannets in New York Harbor, jaegers at Cape May, NJ, storm petrels on the Hudson River and even a red-billed tropicbird are just some of the rare birds sighted along the Atlantic coast after Hurricane Sandy.
Though common over the open ocean, where they spend most of their lives fishing, and though they rarely come ashore, these seabirds represent a fraction of the birds blown off course by the storm.
Birds are well equipped to deal with stormy weather, even hurricanes, said Terry Root, an ornithologist at Stanford University in California. "They can sense even the slightest changes in barometric pressure, which alerts them that a storm is coming well before it hits," she told OurAmazingPlanet.
Out to sea
While most birds sense severe weather and stay grounded, seeking shelter may not be an option for birds that live on the open ocean, or those migrating across the seas.
Yet many birds prove adept at navigating stormy skies, even if that means heading right into the eye of a hurricane, according to Barry Truitt, chief conservation scientist at the Nature Conservancy in Virginia. Truitt has used satellites to help track more than 20 Whimbrels, wading shore birds that migrate semi-annually between breeding grounds in Arctic Canada and winter grounds on the coast of South America. [Top 10 Most Incredible Animal Journeys]
Hurricanes can quickly exhaust birds flying into the storms’ high headwinds, but the tempests can also provide great tailwinds, said Truitt. Last year, he tracked one Whimbrel, dubbed Hope, through Tropical Storm Gert off the coast of Nova Scotia. Hope averaged only 9 miles (14.5 kilometers) an hour into the storm's head winds, but once past the center, she enjoyed a stiff tailwind that sent her zipping along at 90 miles (145 km) per hour.
Carried off course
Not all birds make it through the center of a hurricane with ease. "Ocean-going and migratory birds have evolved to deal with inclement weather, but younger birds, especially those who may be making the passage for the first time, might not know what they are doing,” said Frank Moore, an ornithologist at the University of Southern Mississippi. “A hurricane could have traumatic, negative consequences.”
For one thing, birds face a big risk of becoming entrained, or pulled along, in the strong, circulating winds around the center of a hurricane; the birds could get carried long distances off course, said Paul Sweet, collections manager in the ornithology department at the American Museum of Natural History in Manhattan.
Those birds that do get blown far off course often face an uphill battle for survival, said Glenn Phillips, executive director of the New York City Audubon Society. "They are often weak and exhausted when they land, which makes them an easy target for predators," he said in an interview.
Previous studies have found that bird species in a hurricane's path may experience long-term population losses. One report found that species as far as 60 miles (97 km) from a hurricane's path took up to five years to rebound from the destruction of their forested habitat.
A Canadian study found that the total Chimney Swift population in Quebec fell by as much as 50 percent after Hurricane Wilma in 2005 battered many of them on their southward migration, sending some as far off-course as Western Europe.
Late arrival lessens blow
The Eastern Seaboard of the United States serves as a major migratory route, known as the Atlantic Flyway, for birds passing between breeding grounds in Canada and wintering habitat at points to the south.
While Hurricane Sandy has already affected some birds, Sweet expects that its arrival late in the migration season will help lessen the blow.
"September and October are really the peak months of fall migration in and around the New York City area. Most groups, such as warblers and vireos, that make the big trans-ocean flight to Central and South America have already gone," he said.
Even if most migratory birds dodged a bullet this time, the prospect of bigger and more frequent hurricanes, fueled by warmer ocean waters, doesn't bode well for many species already facing pressure from habitat loss at both tropical winter grounds and northern breeding areas, said Truitt, the scientist at the Nature Conservancy.
"It's hard enough for birds to make a living," said Moore, the Mississippi ornithologist. "Big storms don't help."
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