October 28, 2012
Wyoming

Migratory bats hardest hit by wind turbines

By CHRISTINE PETERSON Star-Tribune staff writer | Casper Star-Tribune | Oct. 28, 2012 | trib.com

Of Wyoming’s 15 resident bat species, three of them are most susceptible to the deadly effects of wind turbines: the hoary bat, the silver-haired bat and the eastern red bat.

They are Wyoming’s only tree-roosting bats, said Douglas Keinath, senior zoologist with the Wyoming Natural Diversity Database.

Because they roost in trees, they can’t protect themselves from the winter cold and wind. This means they are also Wyoming’s only migratory bats.

All other bats hibernate, often in caves or mines where they are protected from the elements.

During migration bats seem to suffer most from barotrauma, when changes in pressure near spinning wind turbine blades explodes the capillaries on the edges of bats’ lungs. The lungs fill with fluid, and the bats drown, Keinath said.

Hoary, silver-haired and eastern red bats are very light. The hoary, the largest of the three, usually weighs less than one ounce. A robin weighs three times as much even though its wing span is the same size.

The three species also have the most fur of any Wyoming bats. In cool climates, their furry wings wrap around their bodies like sleeping bags, Keinath said.

Here is the breakdown on Wyoming’s only migratory bats, and those most at risk to die of barotrauma.

* Hoary bat: Wyoming’s largest bat, its wingspan is more than a foot long. It survives mostly on moths but will also eat large beetles and grasshoppers. Hoary bats roost in conifer trees, often at the edges of clearing. “The bat’s size, shape and coloration mimic pine cones,” Keinath said.

They are strong fliers and are the most widespread of any American bat. They are also the only bat native to Hawaii. Experts believe the hoary bat flew there from mainland North America.

* Eastern red bat: This small to medium-size bat lives mostly on moths, beetles and mosquitoes. Its wing span is between 11 and 13 inches and it weighs about as much as two nickels. It roosts in leaves of trees and hangs from one foot. “Their size, shape, and red coloration mimic a dead leaf,” Keinath said.

* Silver-haired bat: Slightly smaller than the red bat, the silver-haired bat eats small insects such as mosquitoes, flying ants and small moths. Even though it’s North America’s slowest-flying bat, it is still a strong flier and can migrate long distances. It sleeps in loose bark or cavities of trees.