Where do Birds go When it Rains?

A comic strip I recently saw online pondered the question that sits up there in my title.  It noted that people around the world ask this, wondering what the birds do during storms, and hoping that they are safe and dry.  It’s true, you often don’t see many birds out and about during heavy rain.  So, where do they all go?

Like all wild animals, birds have adapted a variety of ways to weather the weather.  Many people think that birds have nests that they use all year for shelter and sleeping, like a rabbit uses its burrow.  Indeed, some birds do have year-round shelters.  Woodpeckers use tree cavities, as do some owls.  Swifts sleep in chimneys, hollow trees and crevices in rocky cliffs all year.  Our abundant neighborhood Carolina Wrens may use their scraggly dome-shaped nests all year for overnight shelter.

Most birds, however, only use nests, birdhouses and tree cavities during the breeding season in spring and summer.  These nests are used as places to hatch their eggs and shelter their babies.  At the end of the summer when the babies are grown, the nests are abandoned.

So, where do all these other birds go when it rains? For the most part, they go to the same places they go at night.  These sheltering and sleeping places are generally known as “roosts.”  Roosts need to serve a dual purpose – shelter from the elements and protection from predators.  Many times, the danger of predation wins out, and birds may roost fully exposed to the weather.  So why would a bird choose to sit out in the open, in the dark of night or driving rain, and how can it possibly stay warm and dry there?

The answer to this lies in one of the most complex and unusual structures found in nature: the feather.  Every bird known to science has feathers, as did many of the ancient dinosaurs.  If you have ever looked at a feather up close, you have seen how fascinating it is, with the hundreds of individual barbs branching from the shaft, the tiny hooks (barbules) that link them together, and the microscopic barnacles that hook the barbules together.  The feather is very strong, yet virtually weightless.

The feather is also an amazingly adaptable structure.  The long, strong feathers of wings and tail, of course, make bird flight possible.  But the lowly body feathers, contour feathers, are equally remarkable.  They overlap each other like perfectly laid shingles; I’ve wondered if the original idea for the shingle roof was inspired by birds and their feathering.  They are also made water-repellent by frequent application of oil from the sebaceous glands that sit at the base of all birds’ tails.  When you see birds preening themselves, they are keeping themselves well oiled and neatly arrayed.

These tightly shingled, meticulously oiled feathers provide all birds with an insulated windbreaker and raincoat.  Birds shed water “like a duck’s back,” or a well-made roof.  The feathers can also be pulled in tight and sleek against the body, or fluffed out full and puffy.  This dramatically changes their insulating value.  Fluffed, they are full of heat-trapping air spaces; sleek, they are thin and heat conducting.  So, a bird can change from a down parka to a lycra track suit, or back, in an instant.

Being so well protected, most small birds in the rain will simply seek a spot where they are sheltered from view and perhaps buffered from the worst of the wind and rain.  Hunkered down, they wait out the storm.  When the rain ends, with a shake, a fluff and some quick preening, they are good as new.

This is also why large birds are often seen roosting right out in the open.  The predators they fear most are not other birds, but mammals.  Raccoons, coyotes and bobcats would love to snatch up a tasty goose or hawk for supper.  So these birds sleep out in the middle of a pond, on top of a high snag or even on a sandbar surrounded by water.  They are impervious to the wind and rain, and any approaching marauder would have to make a whole lot of splashing or shaking before it reached them.

A few years back, we had a vivid demonstration of how immune birds can be to weather.  We had some free-roaming chickens that liked to roost overnight on scaffolding that was under a gutter drip.  One night, when we had freezing rain, in the morning the chickens were sitting happily in their roosts, seemingly unaware that they had ice crusted on their backs and icicles hanging from their tails! They got up and went about their business, with the ice chunks eventually falling off.

The weatherproofing provided by feathers has also allowed birds to flourish in the cold oceans of the Northern and Southern Hemispheres.  The flightless penguins of Antarctica are well known.  The similar (though only very distantly related) auks, murres and puffins of the north retain their abilities to fly.  For these marine birds, as well as the many loons, grebes and diving ducks of freshwaters, feathers serve for more than just insulation.

If you have ever been scuba diving, you will have used a “buoyancy compensator.” This is an inflatable vest which you pump up or deflate, adjusting how much you sink or float in the water.  Diving birds use their feathers as a “buoyancy compensator.”  By adjusting how much air the feathers trap, they can make themselves bob like a cork or sink towards the bottom.

When we were in Oregon last spring, we visited the Oregon Coast Aquarium.  One of their exhibits is an impressive aviary of marine birds where you can watch the murres and guillemots swimming and feeding from underwater.  When they dive to catch the small fish that they are fed, they are entirely wrapped in a glistening envelope of air.  They become agile, fasting-moving, bird-shaped, predatory air bubbles.

Birds may often look small and vulnerable, but when it comes to weathering the storm, even a tiny hummingbird is far tougher than we are.

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