Thursday, November 15, 2012

Basics: Birds Have Natural Ability to Survive Storms

AWASH A protected area for plovers in Lido Beach, N.Y., after a 2009 storm.

In the wake of Hurricane Sandy and the spiteful me-too northeaster, much of the East Coast looked so battered and flooded, so strewed with toppled trees and stripped of dunes and beaches, that many observers feared the worst. Any day now, surely, the wildlife corpses would start showing up ? especially birds, for who likelier to pay when a sky turns rogue than the ones who act as if they own it?

Yet biologists studying the hurricane?s aftermath say there is remarkably little evidence that birds, or any other countable, charismatic fauna for that matter, have suffered the sort of mass casualties seen in environmental disasters like the BP oil spill of 2010, when thousands of oil-slicked seabirds washed ashore, unable to fly, feed or stay warm.

?With an oil spill, the mortality is way more direct and evident,? said Andrew Farnsworth, a scientist at the Cornell Lab of Ornithology. ?And though it?s possible that thousands of birds were slammed into the ocean by this storm and we?ll never know about it, my gut tells me that didn?t happen.?

To the contrary, scientists said, powerful new satellite tracking studies of birds on the wing ? including one that coincided with the height of Hurricane Sandy?s fury ? reveal birds as the supreme masters of extreme weather management, able to skirt deftly around gale-force winds, correct course after being blown horribly astray, or even use a hurricane as a kind of slingshot to propel themselves forward at hyperspeed.

?We must remind ourselves that 40 to 50 percent of birds are migratory, often traveling thousands of miles a year between their summer and winter grounds,? said Gary Langham, chief scientist of the National Audubon Society in Washington. ?The only way they can accomplish that is to have amazing abilities that are far beyond anything we can do.?

Humans may complain about climate change. Birds do something about it. ?Migration, in its most basic sense, is a response to a changing climate,? Dr. Farnsworth said. ?It?s finding some way to deal with a changing regime of temperature and food availability.? For birds, cyclones, squalls and other meteorological wild cards have always been a part of the itinerant?s package, and they have evolved stable strategies for dealing with instability.

Given the likelihood that extreme weather events will only become more common as the planet heats up, Dr. Farnsworth said, ?the fact that birds can respond to severe storms is to some extent a good sign.? Nevertheless, he added, ?how many times they can do it, and how severe is too severe, are open questions.?

Among a bird?s weather management skills is the power to detect the air pressure changes that signal a coming storm, and with enough advance notice to prepare for adversity. Scientists are not certain how this avian barometer works, yet the evidence of its existence is clear.

As just one example, Dr. Langham cited the behavior of the birds in his backyard in Washington on the days before Hurricane Sandy arrived. ?They were going crazy, eating food in a driving rain and wind when normally they would never have been out in that kind of weather,? he said. ?They knew a bigger storm was coming, and they were trying to get food while they could.?

Songbirds and their so-called passerine kin may be notorious lightweights ? if a sparrow were a letter, it could travel on a single stamp ? but that doesn?t mean they?re as helpless as loose feathers in the wind. Passerine means perching, and the members of this broad taxonomic fraternity all take their perching seriously.

When a storm hits, a passerine bird can alight on the nearest available branch or wire with talons that will reflexively close upon contact and remain closed by default, without added expenditure of energy, until the bird chooses to open them again. If you?ve ever watched a perched bird in a high wind and worried, ?Poor squinting thing ? could it be blown away and smashed to bits down the road?,? the answer is not unless the perch is blown away with it.

Scientists have found that many migratory birds, especially the passerines, seek to hug the coast and its potential perches as long as possible, leaving the jump over open water to the last possible moment. But for birds over the open ocean, hurricanes pose a real challenge, and they can be blown off course by hundreds of miles. In fact, ornithologists and serious bird-watchers admit they look forward to big storms that might blow their way exotic species they?d otherwise never see in their lifetime.

Source: http://www.nytimes.com/2012/11/13/science/birds-have-natural-ability-to-survive-storms.html?partner=rss&emc=rss

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