News Column

What Do Birds do During Downpours?

July 29, 2013

Late last Sunday night, I drove home from work through blindingly heavy rain that continued for at least 30 minutes. It made me wonder: Do birds seek super-sheltered branches for sleeping at night in case of heavy rain?

You've probably seen birds merrily eating at your feeders during gentle rains, but what do birds do during downpours, especially downpours that begin well after dark?

"Birds," of course, includes ducks, herons, shorebirds, raptors, songbirds, swallows, woodpeckers, hummingbirds and lots more, and various birds cope with heavy rain in different ways.

Let's limit this discussion to the birds that visit our feeders.

An article in the New York Times, written shortly after Superstorm Sandy, cites Gary Langham, chief scientist of the National Audubon Society in Washington, D.C.

"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," the article says. "Scientists are not certain how this avian barometer works, yet the evidence of its existence is clear."

You've probably witnessed birds becoming noisy and active shortly before a thunderstorm passes through. Somehow, birds know to prepare for nasty weather.

Naturalist Jim McCormac writes a column for the Columbus (Ohio) Dispatch, and he also addressed birds in downpours.

"For the most part, they behave as you or I probably would: They find the densest, most sheltered spots available to ride out the storm. If you could X-ray a thick spruce or matted grapevine tangle during a thunderstorm, you'd probably see a number of songbirds cowering within. Habitual cavity-nesters such as bluebirds and chickadees might retreat to nest boxes or tree holes, and other species will press tight against tree trunks on the lee side of the winds and rain."

Cornell Lab of Ornithology's AllAboutBirds.org confirms: "Birds that normally roost in a cavity, such as chickadees, small owls, woodpeckers, etc., hide out in their cavity. That makes them safe as long as the tree itself doesn't fall down. Birds that roost on branches, such as jays, sparrows, cardinals, crows, etc., tend to perch on a thick branch very close to the trunk on the side most protected from wind and rain. When these songbirds (also called "perching birds") are relaxed, their feet grasp automatically, so they can sleep while tightly clasping the branch."

Jim Eagleman, a naturalist at Brown County State Park, said he's seen birds seek cover from the rain: "We advise our public at programs when asked that birds merely duck under cover, or slip into woodpecker holes, snags, burrows, dens, etc. This is what the (limited) literature reports. ... I have observed titmice latched onto limbs as the winds blow them about, looking like they are hanging on for dear life, and once I saw an entire flock of waxwings duck under cover in an old shelterhouse when it rained buckets."

John Castrale, a bird biologist for the Indiana Department of Natural Resources, said "feathers are pretty waterproof, so brief, light rains do not impact them much and birds can stay pretty dry."

During the night, Castrale said, most songbirds select sheltered roosts. "Because of darkness, they would be reluctant to move from their secure and familiar location. ... Birds are light sleepers so they are most likely awakened by any sudden changes (like a rain event) in their local surroundings." He said songbirds generally "tough it out wherever they are" during a heavy downpour.

Heavy rain can be most deadly for birds, though, when it occurs during nesting season. Young birds are vulnerable to prolonged exposure to rain, and some birds simply build flimsy nests that can't withstand downpours.

Researchers in the Amazon took blood samples of rainforest songbirds and found elevated levels of stress hormones levels on very rainy days. The birds also had high levels of a chemical that indicated the birds were burning stored fat -- a sign that they weren't getting enough food.

Survival of the fittest certainly comes into play, but songbirds have been surviving downpours for thousands of years.

If you want to make this rainy summer easier for them, make sure the habitat of your yard contains shelter, such as a nest box or two, densely leafy vegetation, brush piles and big, old trees with holes where branches have broken.



Source: (c)2013 Herald-Times (Bloomington, Ind.) Distributed by MCT Information Services


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