Endangered North American songbird made remarkable recovery
Copyright 2001
Detroit Free Press
June 29, 2001
By Emilia Askari
DETROIT _ Jerry Weinrich walked through the woods at Camp Grayling in Michigan a few minutes after dawn last week. The wildlife biologist listened carefully to the sounds of a forest awakening.
TUP TUP chee-chee-chee wee wee! It was the call of the Kirtland's warbler, once among the rarest birds in North America.
Before noon, the state Department of Natural Resources specialist knew that this would be a very good year for the warbler, which nests only in the jack pine forests of northern Michigan. In fact, it was the best year since biologists first counted the Kirtland's warbler population in 1951.
In the early 1970s, the bird was one of the first animals protected under the Endangered Species Act. At the time, Weinrich had just begun studying the bird; there were fewer than 170 nesting pairs of them.
Weinrich's dream was to help save the warbler, building its population back to 1,000 nesting pairs. Some biologists thought it couldn't be done. However, Weinrich was an optimist.
On Wednesday, he announced that he had been right. This year's survey by about 30 government biologists and volunteers found 1,085 singing males, an increase of nearly 200 over the previous year.
As recently as 1987, only 167 singing males were found. Since then, the numbers of male warblers heard each year have risen steadily.
Biologists assume that an equal number of females are quietly sitting on their nests while their mates belt out a distinctive song.
"It's not real long but it's very loud," Weinrich said. "They put a lot of effort into it."
The male birds sing in the cool early mornings of mid- to late June and early July to protect their territory of about 8-and-a-half acres from other warblers.
If the annual count of Kirtland's warbler's stays above 1,000 for five years, officials will consider removing the bird from the endangered list. But state and federal agencies must promise to continue the two-pronged strategy that has restored the warbler's population.
The warbler likes 10-year-old pines for its nesting. To ensure a continuing supply of trees of that age, officials must allow the forests to be thinned of older trees by cutting or fire, making room for new growths.
In addition, federal biologists have to corral about 4,000 cow birds in the area. Cow birds lay their eggs in other species' nests, leaving their young to be raised by the hosts, such as the warblers. The aggressive young cow birds can overwhelm their nestmates.
"You can't quit controlling cow birds or creating Kirtland's habitat for a couple of years," Weinrich said. "If you do, the population would go right down again."
For more information about the Kirtland's warbler, check out the Michigan Department of Natural Resource's web site: www.dnr.state.mi.us/