A nighttime summer storm is barreling through as I write this column. Brilliant flashes of lightning illuminate the landscape, as if someone flipped on a bank of giant klieg lights. Seconds later, booming claps of thunder rattle the house and shake the trees.
After a series of intense flash-boom-rattles, an eerie calm briefly settles in. Then the rain hits. Walls of water, propelled almost sideways by ferocious winds, batter the windows and pound the shingles.
It’s weather such as this that makes one grateful for good shelter.
Birds, however, don’t have the luxury of retreating into cozy bungalows during foul weather. So what do they do?
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.
Healthy adult birds are probably going to survive severe bouts of weather. Mortality can spike, however, if savage storms strike during the peak of nesting season. Young birds are vulnerable to prolonged exposure to rain and cold, and flimsy nests can be tossed from trees.
Probably the most threatening types of storms are those that involve hail. Most hailstorms occur in June and July, which are peak nesting periods for songbirds. One of the worst hail-related cases of bird mortality occurred in July 1953, when an estimated 150,000 ducks and geese perished during a severe storm in the western Canadian province of Alberta.
Lightning also strikes birds. An observer once saw a bolt of lightning strike a large flock of migrating snow geese, dropping more than 50 of the birds. Bald eagles have been struck while sitting on their nests, and John James Audubon described two common nighthawks blown from the sky by a lightning bolt.
Bad weather can be tough on birds, but they’ve dealt with it for eons and evolved coping mechanisms that work in most situations. The tremendous drive to migrate, reach nesting grounds and reproduce compels songbirds to push through even the nastiest weather.
Several years ago, I was on South Bass Island in Lake Erie in May — the peak of spring migration. The dominant feature on the island is the 352-foot-tall Perry’s Victory and International Peace Memorial, which is illuminated by powerful lights at night.
I visited the tower one evening amid near gale-force winds and driving rain to see whether I could detect migrant birds passing through the tower’s lights. To my amazement, a steady stream of sparrows, thrushes, warblers and other songbirds would sweep into the sphere of lights, swirl once or twice around the tower, temporarily disoriented by the light, then shoot off to the north over the lake. They then faced a rough 25-mile Lake Erie crossing in weather so nasty that any sailor with a speck of survival sense would be on terra firma and far from his boat.
Far worse than stormy weather are the myriad obstacles that people have placed in the paths of migrant birds — threats that birds haven’t evolved with. Skyscrapers with brightly lighted windows lure nocturnally migrating songbirds. Confused by the lights, birds crash into the buildings and perish by the tens of millions annually.
Lofty communications towers bristle from the landscape and take out scores of birds. A 1,000-foot tower in Wisconsin was studied during 38 years, and 121,560 kills involving 123 species were documented. In the United States, more than 100,000 towers stand 200 feet or taller. Giant wind turbines are a growing threat.
People, far more than any storm, represent the biggest threat to birds.
Naturalist Jim McCormac writes a column for The Dispatch the first and third Sundays of the month. He also writes about nature at www.jimmccormac. blogspot.com.
cdecker@dispatch.com
