On the Fly – Nice Weather for Ducks

What do birds do when it’s raining? A little rain is not a big deal for birds, because their feathers are made of beta-keratin, a water-resistant material. And when birds preen, which they do to keep parasites at bay and to keep those feathers from drying out, they spread a waxy oil over them that makes them still more water-resistant.

So rain is not the inconvenience for birds that it is for humans. In fact, if the weather has been dry for a while, some birds enjoy getting rained on. You can watch ducks open up their feathers to let the rain in, and pigeons will sit on utility wires in the rain and let it wash them off. Songbirds may enjoy a bath in a puddle when the sun comes back out, and hummingbirds will wash themselves off on wet leaves. And consider the earthworms. They need almost constant moisture, which is why they stay underground most of the time. A good rain allows them to move to the surface for a change in diet, which works out well for the birds, too.

Birds do have strategies for coping with the cold temperatures that often accompany rain. They roost in dense foliage, brush piles, thick grasses, and holes in trees, and some birds will snuggle up together to conserve heat. Birds fluff out their feathers for insulation, creating air pockets that retain heat, tucking in their heads and other unfeathered parts. When it gets really cold, they shiver, converting muscle energy to heat. And they can constrict the flow of warm blood to their legs and feet, or even change the flow of blood to move heat from their arteries to their veins. This can reduce heat loss in the extremities by up to 90 percent, which is why a gull can stand on ice without losing too much body heat or freezing its feet. And then there’s the state called “torpor.” A torpid bird has dropped its core temperature and will stay inactive and unresponsive until conditions improve. Hummingbirds do this. The common poorwill does it long and thoroughly enough for it to be called hibernation, which is why the Hopi name for the poorwill means “the sleeping one.”

The birds that live in really cold places migrate in the winter—an extreme solution when you think about it. Can it be worthwhile to leave your territory, expend that much energy, even risk your life? Yes, because it’s not so much about staying warm as it is about following the food. Insects are hard to find in extreme cold, for example, and it’s not easy to fish through ice either. But why go back to the north when the weather warms up? Why not just stay in the tropics? Food and protective plant cover are abundant in temperate zones during the breeding season, and there are fewer nest predators and parasites than in the tropics. And there’s more daylight, which means more time for foraging.

Migrating birds can stay ahead of a storm if they’re strong flyers, but others have to lie low and wait it out. Shorebirds head inland. Songbirds cling to sheltered branches, staying out of the swaying heights: their leg muscles are structured to tighten their toes around their perches, holding them in place in the wind. Other birds find caves or rocky overhangs to hide in, or cavities in trees.

A hurricane or a heavy storm may carry birds a long distance off-course—a misfortune for a misplaced bird, but a boon for birders. You can read about birding in the aftermath of Hurricane Irene on the lively blog 10,000 Birds. Mark Obmascik, author of The Big Year: A Tale of Man, Nature, and Fowl Obsession (the book that the recent movie was based on), describes storm-induced bird fallout as “the stuff of legends” that “looks as if a Star Trek transporter is beaming creatures from outer space and down onto the coast—birds, thousands of birds, come from nowhere. Tree limbs bend with scarlet tanagers. Lawns are carpeted with warblers. Yard bushes with bare spring buds are transformed into Christmas trees laden with brilliant winged ornaments.”

Speaking of the holidays, I’ll close with a note about turkeys. There’s an old and widespread belief that turkeys are so stupid they will stare up at the rain with their mouths hanging open till they drown themselves. This is not true. I have nothing to offer regarding the intelligence of turkeys, but as the people at snopes.com point out, turkeys don’t have binocular vision; their eyes are set on the sides of their heads, so they look sideways at things and hence do not look up at the rain.