Weather extremes take a toll on birds

Article by: JIM WILLIAMS , Special to the Star Tribune
Updated: July 3, 2012 - 2:40 PM

Heavy rainfall and rising waters did in a number of nests. And the heat waves that have followed present added challenges for our feathered brethren.

hide

Common loon nests along the shoreline can be damaged during abrupt flooding.

Photo: Jim Williams, Special to the Star Tribune

Camera Star Tribune photo galleries

Camera view larger

1
comments
resize text
print
buy reprints

Tweet
share

email
Email share

your name

your email

recipients email

+ add a comment add a comment

Our recent weather extremes put birds in the position of win some, lose some. They usually can handle the higher temperatures of summer, but they can have as much trouble as we do when rain floods the countryside.

A few days before the deluge that hit Duluth and the North Shore, I was birding near Lutsen on the Lake Superior shore. A highlight was discovery of a bump of rock just offshore, where herring gulls were nesting.

I counted four nests on which birds were incubating eggs, four sets of chicks small enough to be brooded by their mothers, and scattered empty nests.

Lutsen did not get the extreme downpour that flooded Duluth. The rain was heavy, though, and daylong. When the rain stopped, the bump of rock was bare. A handful of gulls loafed there, but nests, eggs and chicks had been washed away.

Any exposed nest probably was rained to pieces. Birds brooding chicks would have had a hard time keeping the babies warm and dry. Wet chicks would have been potential hypothermia victims. Ground nesters -- ovenbirds, some sparrow species, meadowlarks, bobolinks -- would have been particularly vulnerable.

Water birds that nest on or near water would have contended with a sudden rise in water levels. Loons, for instance, nest on the ground at lake edges. Rain could boost lake levels enough to cover the nest, or to allow waves to pound nests apart.

Grebes build floating nests, gathering grasses and reeds to build a platform that is anchored to a reed or other water plant. Rising water would tear the nests loose, work them to pieces.

The only solution for all of these birds is to renest. Some have done so. Others would not have had time to build a new nest, produce eggs (one per day), incubate and fledge young, and then see them mature for the rigors of migration.

Adult birds saved themselves by seeking shelter from the rough weather.

Coping with the extreme heat that came after the floods posed different problems for birds.

Birds run a higher body temperature than we do. This fuels their high activity level. A certain higher level of body temperature is a good thing. But ground temperatures of 90-plus can be too much of a good thing.

Birds don't sweat. They depend on heat removal by air exchange. This can be as simple as standing tall with wings extended to increase body surface available to the air. It helps that birds lose feathers come summer, getting along with a cooler covering.

Birds will gape and pant when overheating. House sparrows have been measured at 57 breaths per minute at a temp of 86 degrees. That can rise to as many as 160 breaths per minute at 109 degrees.

The latter is an extreme temperature, but close to common this year in prairie regions to our south and west. Prairie birds tuck tight against the shady side of fenceposts to avoid the sun. The birds in your neighborhood seek shelter in the shady interior of tree canopies.

You can help by providing clean water maintained on a continuing basis. Water to drink is important, and birds most likely enjoy a splashing bath or a sprinkler's spray as much as kids do.

Lifelong birder Jim Williams can be reached at woodduck38@gmail.com. Join his conversation about birds at www.startribune.com/wingnut.