Slate explainer: What do birds do during a hurricane?

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As Hurricane Sandy whipped the East Coast, people hunkered down indoors, seeking shelter from the wind and rain. Occasionally they may have peeked out from their fortresses to see birds cartwheeling by like scraps of confetti. How do birds stay safe during powerful storms?

By getting out of Dodge, going with the flow or clinging on for dear life. Because birds are so attuned to shifts in barometric pressure, they can often sense ahead of time when a storm is brewing. That warning leaves them with several options. Some try to outpace the hurricane, coasting ahead on the propulsion of the storm’s outermost winds.

Others, especially pelagic, or ocean-faring, fowl, may take refuge in the calm eye of the weather system, entering at the edge of its spiral and working their way inward. The problem with this strategy is that the birds often get trapped in the squall’s peaceful center until the entire maelstrom dissipates, which means that they can be forced to fly long distances without food or rest, putting them at an increased risk of dying.

Hurricane Wilma, for instance, swept up a flock of North American chimney swifts in 2005 and deposited them almost 700 miles away in Western Europe. And tropical seabirds such as bridled terns, sooty terns, and brown noddies are often blown from their Caribbean homes into the eastern United States, to the delight of birders who wouldn’t normally lay eyes on such exotic species.

While these winged refugees are known as “hurricane birds,” there is another category of strong fliers that ignores the gales altogether, or attempts to force a way through them. In August 2011, scientists used a radio tag to map the path of one intrepid whimbrel across the width of Hurricane Irene. It was migrating from the Arctic to Venezuela, and it was determined.

Instead of moving ahead of, through, or with the hurricane, other birds get as comfortable as they can at home. Cavity nesters such as woodpeckers tend to bide their time in hollowed-out trees. (Of course, this tactic backfires if the storm fells or otherwise damages the trees.) Smaller songbirds that haven’t already evacuated may also perch on branches — the sturdier and more sheltered the better — using their automatically clenching toe muscles to root them in place. Luckily, perching in this fashion does not demand an additional output of avian energy: Birds always clench their toes when they land so that they don’t topple out of trees during sleep.

But there’s little question that avian mortality increases during a hurricane, whether due to starvation, exhaustion, habitat destruction or exposure to pounding rains. In 1989, Hurricane Hugo killed half of the wild parrots in Puerto Rico; a year earlier, Hurricane Gilbert decimated the population of Mexico’s Cozumel thrasher.

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