New Jersey’s population of bald eagles rose to a record high and spread to all 21 counties last year, according to the Department of Environmental Protection. Their revival is thanks to a federal ban on the toxic chemical DDT, long-term protections by state biologists and a network of volunteers who monitor the nests of the iconic birds.
There are now 220 nesting pairs that raised 307 young in 2020, including a record increase of 36 new nests, the DEP said last week.
Those stats represent a strong comeback after the number of eagles dropped to a single nesting pair in the late 1970s because of the toxic insecticide DDT, which made shells so thin they could not be incubated or failed to hatch for other reasons. The chemical was banned by the federal government in 1972 because of its harmful effects on wildlife, including bald eagles.
The birds were also threatened by habitat loss, human disturbance and even hunting, although those pressures have been eased by several conservation laws to protect the species, helped by intensive monitoring of nest sites.
The eagles have landed
About half of the current nests are in Cumberland, Salem and Cape May counties, near to the Delaware Bay and its tributary rivers, where the birds can hunt for fish. Of the new nests, 22 were found in South Jersey, with seven each in central and northern regions; the last county to host a nest was Essex, the DEP said.
“New Jersey’s abundant and growing bald eagle population is a great success story that shows our wildlife conservation work and partnerships are effective,” said soon-to-retire DEP Commissioner Catherine McCabe, in a statement. “Thanks to the hard work of our wildlife conservationists, a commitment to using the best science and our collaboration with our partners, the growing eagle population that has expanded statewide is proof that we have a healthy environment for wildlife.”
The DEP’s work includes mapping the sites of all nests so that their presence can be considered when officials make land-use decisions, said Kathy Clark, Supervising Zoologist with DEP’s Endangered and Nongame Species Program.
The DEP monitors the habitat where the birds hunt, and can apply regulations to those areas too, Clark said. Since about three-quarters of eagle nests are on private land, the DEP also works with landowners to minimize human disturbance to nesting sites, and to sustain favorable habitat.
A nest-monitoring program managed by the Conserve Wildlife Foundation of New Jersey uses about 100 volunteers to observe nests and report the birds’ behavior to DEP biologists. In 2020, volunteers determined that 210 nests raised an average of 1.46 young, above the level of 1 per nest that’s needed to maintain a stable population.
David Wheeler, executive director of the Conserve Wildlife Foundation, said the eagle’s recovery is an inspiring example. “The bald eagle’s return illustrates what is possible for many other rare species when you bring together proactive wildlife management, strong public investment and the unparalleled dedication of biologists and volunteers.”
Although the federal DDT ban began to bring the bird back from the brink of extinction in New Jersey, its recovery has been very largely driven by the DEP, said Eric Stiles, executive director of New Jersey Audubon.
“This is an amazing story New Jersey should celebrate,” he said. “It took banning DDT, passage of the Endangered Species Act and then thousands of dedicated professionals, both paid and volunteers, working tirelessly to bring the species back.”
The conservation effort has been helped by the bird’s status as the national emblem and its majestic appearance, helping to build public support, Stiles said. He said private landowners are often eager to help protect the bird if it nests on their property.
“When I found out that a bald eagle nest was located on a farm, I was so happy because they were so proud of the bald eagles, he said. “That was the best-case scenario.”
The bird’s iconic status also helps explain its spread throughout New Jersey, including in some densely populated and highly urbanized areas, Stiles said. “I have yet to meet a person who sees a bald eagle, and doesn’t put down their phone, and just gaze in amazement,” he said.
Larry Niles, a former DEP scientist, led the department’s eagle-conservation program in the early 1980s, in part by introducing young birds that had been captured from nests in Canada, raised by humans in New Jersey for about a month, and then released.
Conning eagles for their own good
Niles, now an independent wildlife biologist, also took eggs from New Jersey’s only bald eagle nest at the time – at Bear Swamp in Cumberland County – before their shells were broken by unsuspecting parents during incubation. He substituted fake eggs so that the parents continued to nest; artificially incubated and hatched the real eggs, and then put the young birds in the nest in place of the fake eggs.
“We would climb back up the tree weeks later, take the fake eggs out and then put in the chicks, and then the adults just thought that the eggs hatched,” he said. After about five years, the nest became productive again when the older female died and was replaced by a younger that was not contaminated with DDT.
The early conservation program also included a lawsuit filed by the DEP against the developer of a new port on South Jersey’s Cohansey River, where only the second pair of eagles were starting to nest. The DEP won its case on the grounds that the project would have violated the federal Endangered Species Act, Niles recalled.
He said the state has been rigorous in using regulation to protect not only nest sites but also the bird’s foraging grounds. “It’s a really good expression of how committed the state is to protecting its important ecological resources,” he said.
The eagle’s recovery is also a sign that the environment, at least in the bird’s habitat, is clean enough to sustain it, Niles said.
“The eagle reflects the environmental quality of the area around it, and because it has such a large need, it’s a good way of gauging the protection of the land itself,” he said.
But however successful the state has been in using regulation to protect the bird, its recovery could not have happened without the many volunteers who have monitored nest sites and worked to protect foraging areas.
“No one could afford that kind of protection unless it was driven by volunteers,” he said.