As species recover, some threaten others in more dire conditions

GLEN ARBOR, Michigan (AP) – Hidden behind trees near Lake Michigan, two scientists remotely manipulated a robotic owl on the forest floor. As the intruder flapped its wings and whistled, an emery guarding its nest in a nearby pine darted overhead, emitting high-pitched, rapid-fire calls for help.

The little hawk dived towards the enemy and into a net that Smithsonian interns Tim Baerwald and Zachary Bordner had stretched between steel poles. They gently untangled the brown-stained emery, then attached a leg band and backpack drive unit so the researchers could track the mother bird’s movements.

“As long as it’s assembled correctly, it will have a long and happy life,” Baerwald said before Bordner released the emery, which returned to his nesting tree.

The mission will improve knowledge of a species still recovering from a significant decline caused by pesticides, including DDT, which was banned in 1972 after harming many birds of prey. Additionally, he is helping the managers of Sleeping Bear Dunes National Lakeshore protect the plover, an endangered shorebird. that emery kills and eats.

“Merlins are a great threat to their recovery,” said Nathan Cooper, a research ecologist at the Smithsonian’s National Zoo and Conservation Biology Institute.

The situation is ironic: a struggling species rebounds thanks to restoration efforts, only to make things worse for others in danger by looting or beating them for food and living space. Similar circumstances have occurred elsewhere, challenging wildlife experts who want everyone to thrive in healthy, balanced environments.

For example, the return of the iconic bald eagle has put rare waterfowl under pressure. The resurgent peregrine falcon threatens California’s lesser terns and western snow plovers taking refuge at naval bases near San Diego. And, off the coast of California, attacks by protected white sharks hinder the recovery of threatened sea otters.

Gray seals formerly on the verge of extinction in New England waters now occupy some beaches in Massachusetts by the hundreds. The 800-pound mammal’s return has raised concerns about vulnerable fish stocks.

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Such unintended consequences don’t necessarily reveal flaws in the Endangered Species Act or U.S. conservation programs, experts say. Rather, they illustrate the complexity of nature and the importance of protecting biological communities, not just individual species.

“Clearly there are occasions when we get these species conflicts that we are trying to protect,” said Stuart Pimm, extinction specialist at Duke University. “But is that a major conservation concern? No.”

Species recoveries can produce trade-offs, as some animals are more adaptable than others to changes in climate or landscape, said Bruce Stein, chief scientist of the National Wildlife Federation.

“A lot of ecosystems where these things happen are a little out of place at first because we have altered them in some way,” Stein said. “With climate change, there will be winners and losers. The losers will tend to have specific habitat requirements, narrow ecological niches and will often be those already in decline. “

The Great Lakes region has around 65-70 pairs of sand-backed, ring-necked sand plovers, which flutter along the beaches nibbling small marine animals and eggs. They are among the three remaining North American populations, their decline is mainly caused by habitat loss and predation.

Meanwhile, Merlin’s numbers in the region have increased. Over the past 10-15 years, they are suspected of killing at least 57 adult plovers, Cooper said.

While officials have shot some merlins, they are looking for non-lethal controls. Data from the transmitters’ backpacks could help determine if it’s worth trying to capture and transfer them, said Vince Cavalieri, a biologist at National Lakeshore.

EAGLES THREATEN RARE BIRDS

The recovery of America’s national bird, the bald eagle, is a triumph. But in a coastal area of ​​Maine, the large bird of prey poses a problem for America’s only breeding population of large cormorants.

“When disturbed by eagles, adult cormorants blush and leave their nests,” said Don Lyons, a conservation scientist at the National Audubon Society’s Seabird Institute.

Then gulls, crows and crows rush to devour cormorant eggs and chicks. “If this happens repeatedly, an entire colony can fail,” Lyons said.

His team organizes volunteers to camp near cormorant gatherings to scare away the eagles.

In Southern California, terns and snow plovers are no match for peregrine falcons, which like eagles recovered after the DDT ban. Such pesticides are overrun in food chains and cause large birds to produce thin-shelled eggs, which females crush when trying to incubate them.

The San Diego Zoo and Wildlife Alliance seeks to protect endangered birds by hiring a falconer to capture problem pilgrims, keeping them in a detention facility over the winter, or releasing them in Northern California. Some find new territory, while others go back, said Nacho Vilchis, a conservation ecologist.

“If there’s a real bird problem that keeps coming back, we might ask for permission for lethal removal, but only rarely,” Vilchis said.

Hunting and bounties devastated New England gray seals. Saved by the Marine Mammal Protection Act of 1972, the population has rebounded by the tens of thousands.

Fishing groups say seals could threaten cod stocks that regulators are struggling to rebuild after decades of overfishing.

The Coastal Ecosystem Alliance, based in Fairhaven, Massachusetts, wants to weaken the protection act to allow hunting and slow the growth of the seal population, said council member Peter Krogh.

“Gray seals are certainly this case where recovery has been both cause for celebration and cause for concern,” said Kristina Cammen, a University of Maine marine mammal scientist who says they are less dangerous to fish populations. than humans.

SEALS, CORMORANTS BEEDEVIL PESCATORI

Like the fight over seals and cod, there are other instances where reviving species can be more of a nuisance to people than a threat to other wildlife.

Fish farmers in the south and fishermen in the Great Lakes and Pacific Northwest have long complained about the double-crested cormorant, a dark-feathered underwater bird that feeds on catfish, perch, salmon and other species. valuable.

The cormorants did so well after the DDT ban that agencies tried to restrict them in some places with egg oil, nest destruction, and even shooting, attracting lawsuits from conservationists who claim the birds are a goat. atoning for human actions that harm fish.

“They are part of our bird community and ecosystems, and they need a place for them,” said Dave Fielder, a fisheries research biologist at the Michigan Department of Natural Resources. “But when their numbers are so high that they potentially decimate recreational fishing, that’s a problem.”

Wild turkeys were widespread throughout North America prior to European settlement, but by the 1930s they had dwindled by the tens of thousands, disappearing from many states. They are now hunted in 49 states and are so common in New England that they often cause traffic problems.

Some hunters claim that hungry turkeys are outclassing grouse, which are decreasing in parts of their range, such as the Upper Midwest. But scientists point to habitat loss and climate change.

The National Wild Turkey Federation is helping move turkeys from states in abundance – such as North Carolina, Maine and West Virginia – to Texas and others that could use more, said Mark Hatfield, national director of conservation services.

“If you introduce hunting for localized wild turkeysimmediately reduce the problem with overabundant turkeys, ”Hatfield said.

NATURE AT WORK

Conflicts between recovering and struggling species don’t always mean something is wrong, scientists say. It may reflect a return to how things were before humans got in the way.

“When a population returns to the point where it has the same interactions with other organisms as before it collapsed, it’s nature at work,” said John Fitzpatrick, director emeritus of Cornell University’s Laboratory of Ornithology.

The bald eagle is “challenging our preconceptions about what’s normal” for prey like large cormorants in New England and common murres on the west coast, which might have been less abundant before the eagles’ decline, Audubon’s Lyons said. Society.

The recovery of the eagle “complicates the conservation of some other species,” Lyons said. “But their recovery is such a wonderful result … it’s a welcome complication.”

Predator-prey relationships are complex, and taking action can be tricky, said Stein of the wildlife federation. It is often wiser, she said, to focus on protecting habitat and reconnecting fragmented landscapes to promote natural migration rather than “moving things willy-nilly.”

But environmental scientist Ian Warkentin, a merlin specialist, said there may be ways to help struggling species without being burdensome. Larger hawks, such as peregrines sometimes used to chase birds from airports, could be deployed to chase away pebbles from plover nesting areas.

“I fall over to the side of the fence saying we should do everything we can … to help recover the species we have caused so much pain for,” said Warkentin, of the Grenfell Campus at Memorial University in Newfoundland.

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Larson reported from Washington, DC and Whittle reported from Portland, Maine.

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Follow Flesher on Twitter: @JohnFlesher; Larson @LarsonChristina and Whittle: @pxwhittle

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