By MIKE CATALINI | Associated Press

ELIZABETH, N.J. — After rebounding in recent decades due to conservation efforts, the number of once-imperiled peregrine falcons in the U.S. has been dropping again in some places due to the bird flu that has decimated other avian populations in recent years.

Although falcons in coastal parts of the country have been hit hard, researchers say others that set up camp in some of the country’s biggest cities appear to be thriving, showing the world’s fastest bird has acclimated to living among people. They’re also amassing fans, as legions of devotees follow along on webcams each spring as the falcons progress from hatching to leaving the nest.

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“Wildlife can really adapt to these harsh urban environments,” said Christopher Nadareski, research scientist with the New York City Department of Environmental Protection “That’s the key here, is that despite these harsh living conditions for them, they still find ways to survive.”

A rise and fall in fortunes

Peregrines are expert hunters who feast on other birds. With large eyes and bright yellow feet armed with needle-sharp talons, they fly to great heights before diving on unsuspecting prey, sometimes reaching speeds greater than 200 mph (322 kph).

Their populations declined with the use of the pesticide DDT, which infiltrated the food chain and made their shells too weak to hatch. By the 1960s, peregrines disappeared from the eastern half of the country.

But in 1972, DDT was banned, and conservationists began bringing the birds back from the brink. They came off the federal endangered species list in 1999. Nesting pairs in New Jersey, for example, went from fewer than five in 1980 to nearly 45 by 2021.

Their numbers began dropping again, though, with the bird flu outbreak.

The drop has been particularly severe among coastal peregrines, which feast on ducks, geese and other waterfowl that tend to congregate in great numbers and, thus, allow disease to spread more easily, said Kathy Clark, head of New Jersey’s Endangered and Nongame Species Program. Although bird flu is suspected as the cause of many coastal New Jersey nests emptying out, researchers have only been able to recover some of the dead falcons’ carcasses, she said, noting that many of those tested positive for the disease.

Coastal peregrines in other states, including California and Virginia, have also seen declines, with bird flu suspected. It’s not all doom and gloom, though, as New York Department of Conservation wildlife biologist Angelena Ross said enough juveniles are moving into coastal areas to begin replenishing the numbers.

Movin’ on up

Peregrines that made nests among the glass and steel of big cities seem to have avoided the worst of the bird flu outbreak decimating their country cousins.

City falcons, which eat songbirds and pigeons among other birds, haven’t seen the same declines, Clark said. And they’ve successfully added buildings and bridges to the their natural habitats, which include places like the Delaware Water Gap and the Palisades overlooking New York from the New Jersey side of the Hudson River.

Some even made a home on the busy George Washington Bridge, where scientists recently fitted chicks with anklets for tracking. New York state conservation officials estimate that the Big Apple has the largest urban population of peregrines around.

“We’re starting to see increases in success so that in New York City, we are at the point where we’re probably the most concentrated, populated peregrine falcon nesting in the whole world at this point. We have about 30 nesting pairs,” Nadareski said.

‘Symbol of hope’

The bird’s popularity, tethered in large part to its status as the world’s fastest, has soared recently, with thousands following live cams of peregrines around the country.

With plenty of downtime between moments of drama — a mauled woodpecker here, a blue jay head there — the chicks start mimicking their parents, flapping their wings and grabbing nest detritus with their talons around May.

May is also when East Coast biologists band the birds so they can be tracked.

In New Jersey, Wurst and Clark were among the crew that recently ventured high up onto the roof of the Union County Courthouse in Elizabeth to retrieve and four young chicks for banding as their parents swooped at them, using feather dusters to ward off the angry birds.

“Some individuals are more aggressive than others,” said Ben Wurst, a biologist with Conserve Wildlife Foundation of New Jersey, at a recent chick banding in Elizabeth. “Normally they just kind of bonk you.”

They put the young birds in canvas totes to carry off the roof for a checkup and to attach their bracelets, which have an individual number so they can be tracked. Three females and one male chick made up the clutch, Clark said.

“These birds are going to be the ones to repopulate — hopefully,” Clark said. “It’s a great symbol of hope.”

Associated Press videojournalist Joseph Frederick in New York contributed to this report.