Trending
The Associated Press
GLEN ARBOR, Mich. -- In a forest near Lake Michigan, two scientists attached a backpack tracking device to a merlin they'd lured into a net. The mission: help prevent the predatory species from gobbling up piping plovers -- highly endangered shorebirds that nest nearby.
Merlins themselves were going downhill decades ago but are recovering, thanks to bans on pesticides such as DDT. That's good for them -- but not for plovers in the Great Lakes region, where only 65 to 70 pairs remain. The small falcons are "are a big threat to their recovery," said Nathan Cooper, a research ecologist with Smithsonian's National Zoo and Conservation Biology Institute.
The situation is ironic. A troubled species rebounds thanks to restoration efforts, only to make things worse for others in peril by preying on them or outcompeting them for food and living space. Similar circumstances have turned up elsewhere, challenging wildlife experts who want them all to thrive in balanced, healthy environments.
For instance, the iconic bald eagle's comeback has pressured rare water birds. Resurgent peregrine falcons menace endangered California least terns and Western snowy plovers that take refuge at naval bases near San Diego. And, off the California coast, attacks from protected white sharks hinder recovery of threatened sea otters.
Gray seals previously on the brink of extirpation in waters of New England now occupy some Massachusetts beaches by the hundreds. The 800-pound mammal's return has raised worries about vulnerable fish stocks.
Such unintended consequences don't necessarily reveal flaws in the U.S. Endangered Species Act or conservation programs, experts say. Rather, they illustrate nature's complexity and the importance of protecting biological communities, not just individual species.
"Clearly there are occasions when we get these conflicts between species that we're trying to protect," said Stuart Pimm, a Duke University extinction specialist. "But is it a major worry in conservation? No."
Species recoveries can produce tradeoffs, since some animals are more adaptable than others to changes in the climate or landscape, said Bruce Stein, scientist with the National Wildlife Federation.
"A lot of ecosystems where these things are occurring are a little out of whack to begin with because we've altered them in some way," Stein said. "With climate change, there are going to be winners and losers. The losers will tend to have specific habitat requirements, narrow ecological niches, and often will be the ones already declining."
Smithsonian interns Tim Baerwald and Zachary Bordner snared the merlin at Sleeping Bear Dunes National Lakeshore with help from its natural enemy: a great horned owl. This one was dead but fitted with remote-control devices to make it hoot and flap its wings.
The merlin darted overhead, sounding high-pitched, rapid-fire distress calls. It dove into a net stretched between steel poles. The scientists gently disentangled the brownish-speckled female, then attached the tracker and a leg band.
"As long as it's fitted correctly, she'll have a long and happy life," Baerwald said before Bordner released the merlin, which zipped back to its nesting tree.
Merlin numbers in the region have jumped since the DDT ban in 1972. They're suspected of killing at least 57 adult piping plovers in the past 10 to 15 years, said Cooper of Smithsonian.
The sandy-backed, ring-necked plovers skitter along beaches nibbling tiny marine animals and eggs. They're among three remaining North American populations, their decline caused primarily by habitat loss and predation.
While officials have shot some merlins, they're looking for non-lethal controls. Data from the transmitter backpacks might help determine whether capturing and relocating them is worth trying, said Vince Cavalieri, a biologist with the national lakeshore.