Despite comeback, warbler needs help

The Kirtland warbler, an endangered songbird, perched in the jack pine forests of northern Michigan. Its strict habitat requirements only allows it to nest and breed in a handful of places. (John Flesher/Associated Press)

MIO, Mich. - Squeezing between tight rows of jack pines, Sarah Rockwell unfurled what resembled a finely meshed badminton net suspended between two metal poles. A perfect device for capturing a rare Kirtland's warbler for study without injuring the delicate songbird.

But the wily female the scientists were targeting steered clear of the net, despite the lure of a recorded male's rapid, melodious chirp piping repeatedly from a boom box.

"Sometimes it happens," Rockwell said with a sigh after a fruitless half-hour.

Her luck wasn't always that bad. The doctoral student with the Smithsonian Migratory Bird Center in Washington and her colleagues netted about 130 Kirtland's warblers this summer in the sandy flatlands of northern Michigan, part of a decades-old effort to spare the endangered creature from extinction.

It's a mission that, despite considerable progress, may never end. The Kirtland's warbler appears destined forever to need human assistance for survival.

The half-ounce bird has such strict habitat requirements that it nests and breeds in only a handful of places - primarily jack pine stands in Michigan's northern Lower Peninsula. Those forests are managed to meet the warbler's needs, while a campaign is waged to limit the population of its mortal enemy, the brown-headed cowbird.

"We've gotten the bird to more sustained levels, but it's still a battle every year," said Chris Mensing, a biologist with the US Fish and Wildlife Service in East Lansing. "We're going to have to continue our management programs . . . in perpetuity."

That may be the case for most of the 1,353 animals and plants on the federal endangered species list. Before "delisting" a species, government biologists must conclude their populations have recovered.

Mike Scott, a biologist with the US Geological Survey and the University of Idaho, contends the Kirtland's warbler illustrates why it no longer makes sense to think of endangered species as simply recovered or not recovered. He proposes a new category of "conservation-reliant" species that could be removed from the endangered list but still get long-term protection. Such a designation could include about 80 percent of presently listed species, he said.