The double-crested cormorant, a voracious fish-devouring bird that was vanishing only 35 years ago, has made a triumphant comeback. So much so that several states now want the bird dead.

Pennsylvania is the latest to try to kill the cormorant, which has targeted catfish hatcheries in the South, angered anglers in the Great Lakes and killed every tree on a Vermont island.

In the coming days or weeks, federal wildlife sharpshooters will head out to the state-owned Wade Island, near Harrisburg, in the middle of the night and use air rifles and suppressed .22-caliber rifles to try to cull up to 50 of the more than 120 cormorants believed to be nesting there.

Pennsylvania wants to stop the shiny black birds from stealing nesting space from two birds on the state's endangered list: great egrets and black-crowned night herons.

"It's a means of trying to give the great egret and black-crowned night herons some breathing room," said Jerry Feaser, spokesman for the Pennsylvania Game Commission.

Until a federal regulation approved in late 2003 loosened the rules, the legal killing of cormorants was mostly confined to southern states, where hatchery owners could kill them to protect their catfish.

Under the new rules, seven states brought in federal wildlife authorities to kill cormorants, hoping to protect their fish, trees and other birds. The U.S. Fish & Wildlife Service says Pennsylvania, Wisconsin, Mississippi and Ohio are introducing programs this year.

In 2005, federal authorities reported killing just over 13,000 double-crested cormorants, a fourfold increase from a year earlier. Cormorants now number an estimated 2 million in North America.

Vermont will be shooting cormorants for the third straight year in an effort to regenerate cottonwoods, white pine and other trees on Young Island in Lake Champlain. Cormorants on the six-acre island helped kill the trees by stripping them of twigs for nests.

In Great Lakes states, the cormorant population has exploded, competing with anglers for fish such as perch and walleye and hurting tourism. Minnesota is killing cormorants at one of the state's most popular fishing spots, Leech Lake, where they are blamed for making the prized walleye harder to catch.

"I've seen an area one time that's probably a good mile long and it was just solid cormorants," said Walker, Minn., fishing guide Tom Wilson, who estimates he has lost up to three-fourths of his business since 2002. "They were up in the shallows and were feeding on everything."

The cormorant can be mistaken for a duck or a goose when it floats on the water, but when it spreads its wings to a 4-foot span, it can be imposing, like a gargoyle — with a spray of head feathers that stick up like a bad haircut.

The birds winter in the South and nest in the north, mostly around the Great Lakes, on the Canadian prairies and along the coasts.

Before 1972, cormorants were disappearing. Anyone was allowed to shoot them and the pesticide DDT made their eggshells so thin that adults often accidentally crushed their young.

But the federal government began protecting the birds in 1972 and outlawed DDT soon after, bringing them back from the brink.

Expanding fish hatcheries and growing populations of small fish in the Great Lakes also helped, providing better sources of food, said Shauna Hanisch, a Fish & Wildlife Service biologist.

In the Great Lakes alone, the cormorant population has rebounded from 89 nests to more than 110,000.

"Cormorants went away for a generation of people and now they're back," said Diane Pence, a Fish & Wildlife Service biologist. "And so we have a generation that hasn't experienced the number of cormorants that used to exist."

Pennsylvania wildlife officials tried and failed to lure egrets from Wade Island to a neighboring island two years ago before deciding to kill the cormorants.

Still, Stacy Small of Audubon Pennsylvania said the cormorant's reputation for destructiveness — which she said is undeserved — has made states quick to kill the birds before pursuing other options.

"I think it's a somewhat drastic measure," she said.