Staff Writer


Bald eagle numbers continued to increase in New Jersey in 2017, with 178 nest sites monitored, up from 172 last year.

But the number of successful fledglings fell to 190 from 216 last year, said state Division of Fish and Wildlife biologist Kathleen Clark, coauthor of the 2017 New Jersey Bald Eagle Project report by the division and the Conserve Wildlife Foundation of New Jersey.

“We’ve been on quite a ride with significant increases in eagles every year. Now it looks like the population is starting to stabilize,” Clark said. “There are still new nests getting established every year, but there may be other factors starting to come into play, like competition, and some are settling into areas that may not be optimum.”

Three of the 19 dead or injured eagles found this year on the ground appeared to have been hurt or killed in fights with other eagles, she said.

“It’s something we have only seen in the last three to four years,” said Clark. “There are going to be fights over the best nest locations. Newly minted 5- or 6-year-olds come back and try to get their own nests going. Maybe unwisely, some try to take on an established pair.”

Electrocution and injury from flying into electric wires was the most common cause of death of those found. Clark said Atlantic City Electric has cooperated in making changes at locations where eagles have died.

“When you really look at power lines … there’s usually three lines kept separated all at about the same level, called phase lines,” Clark said. If a bird somehow connects two of those phase lines, it gets shocked.”

Of the 178 nests, 153 produced eggs and 25 were territorial or housekeeping pairs, the report said.

The four-year-old telemetry program, which fits some young birds with electronic transmitters, has shown fledglings often range far from New Jersey just weeks after their first flight.

Males tend to return to their home territory more than females, Clark said.

Nacote, a male who fledged in 2014, spent much of the rest of that year in a remote area of Quebec, the report said. He returned to southeastern New Jersey in 2015, has stayed since and has been photographed several times at the Edwin B. Forsythe National Wildlife Refuge in Galloway Township.

Two females, on the other hand, fitted with transmitters in 2012 and 2013, have not returned home. One went to the Chesapeake Bay area in Maryland before eventually flying to Maine and staying in New England. The other also headed to the Chesapeake, then to Canada before returning to Maryland.

“I’ve concluded that, just after learning to fly, they make one big movement,” said Clark. “We’ve had birds go in each of the cardinal directions. It does seem random. Prior to satellite tagging, we always thought young eagles only went south, especially to the Chesapeake Bay, which is an important eagle area.”

Twenty-one new eagle pairs were found this season, the vast majority of which were in the southern part of the state.

“The Delaware Bay region remained the state’s eagle stronghold, with roughly half of nests located in Cumberland and Salem counties and the bayside of Cape May County,” the report said.

Clark said the Delaware Bay area has tidal rivers that provide lots of fish and waterfowl to eat. And there is an abundance of land already in conservation that makes great bald eagle habitat.

“We are really lucky to have a lot of publicly owned land in the Delaware Bay region,” she said.

Seventy-eight percent of the nests with eggs fledged young, for a total of 190 eagle fledglings, the report states.

That’s a productivity rate of 1.25 per active and known-outcome nest, above the required range of 0.9 of 1.1 young per nest for population stability.

Use of the pesticide DDT, which made the eggs of eagles and other raptors too thin to withstand normal incubation, caused the numbers of nesting eagle pairs in the state to fall to one by 1970. It was in Bear Swamp in Downe Township, Cumberland County.

Use of DDT was banned in the U.S. in 1972, but the number of nesting pairs didn’t start to increase until the 1980s, according to the report, after state biologists began a recovery effort.

By 1982, the single pair of eagles in Bear Swamp had failed to fledge young for six years. So state biologists removed the egg produced that year, incubated it and placed the chick back in the nest.

Artificial incubation and fostering of chicks continued until 1989, when the female of the pair was replaced and the pair was able to hatch its own eggs.

State biologists also started a hacking project in 1983 that released young eagles into New Jersey from other states over eight years.

Mortality rates are as high as 80 percent in young eagles, the report said, and eagles don’t start reproducing until they are about 5. So the recovery was slow in the beginning. It really started to take off after 2000.

Now, one of the big problems is human disturbance around nest sites, as about 70 percent of nests are located on privately owned land, Clark said.

That and habitat loss are the greatest threats to the species in New Jersey, according to the report.

Disturbance is any human activity that causes eagles to change their behavior. Studies have shown people on foot result in the strongest negative reaction.

“When eagles change their behavior in reaction to people, they cease doing what is best for their survival and the well-being of their eggs and young,” the report said.

That’s where volunteers can help.

They observe nests from a safe distance, and the state educates the public and sets up safe viewing areas to minimize the stress on the birds. Volunteers record data such as number of birds, behaviors, incubation, feeding and more.

If needed, nests are protected with barriers or posted signs, and biologists work closely with landowners and managers. State conservation officers enforce protection and provide routine assistance.

Biologists enter the nest site to band nestlings when they are between 5 and 8 weeks old. They climb the tree, place nestlings into a large duffel bag and lower them one at a time to the ground. A team records measurements and bands each eaglet.



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number of bald eagle chicks fledged 2017/2016


number of nests monitored 2017/2016


number of nests with eggs 2017/2016


number of nests producing fledglings 2017/2016


new eagle pairs 2017/2016


new eagle pairs in South Jersey 2017/2016

Source: New Jersey Bald Eagle Project reports

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Of the 19 bald eagles found grounded in New Jersey in 2017:

8 died of likely electrocution

4 died of illness, other injury or birth defect

3 died of likely fight with another eagle

2 died of vehicle strike

2 found alive and treated

Source: New Jersey Bald Eagle Project, 2017


Contact: 609-272-7219 Twitter @MichelleBPost

Staff Writer

In my first job after college got paid to read the New York Times and summarize articles for an early online data base. First reporting job was with The Daily Record in Parsippany. I have also worked in nonprofits, and have been with The Press since 1990.

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