NEWPORT, N.J. - In 1981, in a swampy no-man's-land in southern Cumberland County, experts spied New Jersey's only known pair of mated bald eagles and feared they might be its last.

Now, state biologists are heralding a milestone: There are more than 100 pairs of American bald eagles nesting in the Garden State, according to data released last week by the New Jersey Department of Environmental Protection.

Eighteen of the state's 21 counties have at least one active nest, officials report.

By the early 1980s, the majestic bird of prey that symbolizes this nation had been exposed to the pesticide DDT for decades. The eagles consumed it in the food chain, which altered their ability to produce eggs that could survive the weight of the nesting parents.

In 1963, researchers counted only 417 nesting pairs of bald eagles in the country. Four years later, the species was labeled endangered in most states. Though DDT was banned in 1972, the number of eagles continued to fall.

By the time that lone pair of bald eagles was cataloged atop a stick-and-mud perch in the remote Dividing Creek section of Downe Township, the DEP already had mounted an aggressive campaign to fool Mother Nature.

Biologists diverted the attention of the eagle parents from the nest long enough to remove the thin-shelled eggs and replace them with fakes. The eggs then were taken to a farm in Patuxent, Md., and incubated by chickens, said Kathy Clark, a longtime DEP biologist. At two weeks old, the hatchlings were returned to Dividing Creek to be nurtured by the eagles.

The success of the DEP's Endangered and Nongame Species Program spurred other restoration projects. For about seven years, until the early 1990s, the DEP imported five- to eight-week-old eaglets from Manitoba. About 60 were raised in elevated cages in a Cumberland County swamp. They had a minimum of human contact so they could be released into the wild, Clark said.

Some of the birds, which were banded before being released, can still be found in South Jersey, Clark said.

New Jersey's efforts have put the state, along with Pennsylvania and New York, at the forefront of eagle recovery, according to officials.

This year, state biologists fitted a pair of chicks hatched at Merrill Creek Reservoir in Warren County with solar-powered transmitters that allow them to be tracked by satellite. The public can follow the eaglets at http://tinyurl.com/merrillcreek.

Last January, as eagles prepared for breeding season, the DEP counted 102 pairs actively nesting in New Jersey and as many as 11 pairs establishing nesting territories.

The count revealed a record 22 new nests: 16 in South Jersey, two in the central part of the state, and four in North Jersey.

Statewide, 75 percent of bald eagle nests produced offspring, with 119 chicks hatched, according to the mid-winter survey.

Overall, 238 eagles were counted, 28 percent fewer than in 2010. Officials say the lower number may be due to high winds and record snowfall that could have impaired observation of the birds.

"The recovery of the bald eagle from one nesting pair in an isolated swamp in Southern New Jersey in the early 1980s to more than 100 pairs today is a truly remarkable success story that is a testament to the excellent work that has been done to manage the species and to how far we've come as a state to restoring and protecting our environment," state DEP Commissioner Bob Martin said in a statement.

Despite that success, the bald eagle remains endangered in New Jersey. (It was removed from the federal endangered-species list in 2007, and the U.S. Fish and Wildlife Service is overseeing a 20-year monitoring program.)

The highest concentrations of nests are on the Delaware Bay shoreline and along the Maurice and Cohansey Rivers in Cumberland County. While some nests are obvious and get a lot of attention from birders, most of the locations are highly guarded secrets, Clark said.

But the eagles still need the public's attention - and financial support. The Bald Eagle Research and Management Project is funded by those who donate a portion of their New Jersey income-tax refund to wildlife conservation or who purchase Conserve Wildlife license plates. The project also is supported by federal grants and the Conserve Wildlife Foundation of New Jersey.

Cumberland County will host its annual Winter Eagle Festival on Feb. 11. The event, at the fire hall in Mauricetown, will feature trail walks, birding lectures by naturalists, and exhibits and activities for children. For information: 856-453-2177 or http://tinyurl.com/mauriceville.
Contact staff writer Jacqueline L. Urgo at 609-652-8382 or 609-652-8382 or jurgo@phillynews.com.