Survival skills Biologists studying the aftermath of Hurricane Sandy say there is little evidence to show that birds have suffered the sort of mass casualties that occurred in environmental disasters such as the oil spill of 2010. This is because of the weather management skills that birds have, writes Natalie Angier
In the wake of Hurricane Sandy, 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. 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.
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 per cent of birds are migratory, often travelling thousands of miles a year between their summer and winter grounds,” said Gary Langham, chief scientist of the National Audubon Society in Washington.
Humans may complain about climate change. Birds do something about it. 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 become more common as the planet heats up, Farnsworth said, “the fact that birds can respond to severe storms is to some extent a good sign.”Fully equipped
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, Langham cited the behaviour 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. Songbirds and their so-called passerine kin may be notorious lightweights, 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 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.
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 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 would otherwise never see in their lifetime.
Hurricane Sandy did not disappoint them. It pulled in a far more diverse group of birds than the average hurricane, and websites were alive with thrilled reports of exceptional sightings – of the European shorebird called the northern lapwing showing up in Massachusetts; of Eastern wood-pewees that should have been in Central and South America appearing again in New York and Ontario; of trindade petrels, which normally spend their lives over the open ocean off Brazil, popping up in western Pennsylvania; and of flocks of Leach’s storm-petrels and pomarine jaegers, arctic relatives of gulls, making unheard-of tours far inland and through Manhattan.Once the storm had passed they took off, presumably heading back to where they wanted to be. “Birds have tremendous situational awareness,” said Bryan D Watts, director of the Center for Conservation Biology at the College of William and Mary in Virginia. Researchers have begun tagging birds with GPS devices and tracking them by satellite to gain detailed insights into how they accomplish their migratory marathons and what they do when confronting a storm.
Waiting it out
In preparation for a possible offshore wind development project, Caleb Spiegel, a wildlife biologist with the US Fish and Wildlife Service, and his colleagues at the Bureau of Ocean Energy Management have attached transmitters to the tail feathers of several types of migratory birds, including the northern gannet, a big waterfowl with a spectacular fishing style of falling straight down from the sky like a missile dropped from a plane. One of the gannets was approaching the southern shore of New Jersey at just the moment Hurricane Sandy made landfall there, and Spiegel could catch the bird’s honker of a reaction.
Making a sharp U-turn, it headed back north toward Long Island and then cut out to sea along the continental shelf, where it waited out the storm while refueling with a few divebombs for fish. In a renowned tracking study that began in 2008, Watts and his colleagues have followed the peregrinations of whimbrels, speckled brown shorebirds with long curved beaks that breed in the subarctic Hudson Bay and winter as far south as Brazil. Because whimbrels regularly pass through the “hurricane alley” of the Caribbean and other meteorological hot spots, Watts said, “we’ve tracked many birds into major storms.” In August 2011, the researchers marvelled at the derring-do of a whimbrel named Hope as it encountered Tropical Storm Gert off Nova Scotia, diving straight into the tempest at 7 mph and emerging from the other side at 90 mph.
Not long after, the scientists cheered as four other whimbrels successfully navigated their way through Hurricane Irene. The joy was short-lived. In September 2011, two of the four Irene survivors sought refuge from another storm by landing on the island of Guadeloupe, where they were shot by sport hunters. Watts has since discovered to his dismay that throughout the Caribbean islands, hurricane season is considered hunting season.