Written by Bill Barlow Friday, May 10, 2013 12:32 pm
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Not long ago, the chances of seeing an eagle in New Jersey were almost infinitesimal. A little while ago, a reporter saw five in one day in Atlantic County, two flying over a Parkway entrance, one high above a group of circling buzzards, and two more flying off a tree in the parking lot of a trailhead. Those two were immature, but definitely bald eagles.
“Eagles have slowly been recovering from the bad old days of DDT, and this protection has started to pay off,” said Mike Crewe, the program director at the Cape May Bird Observatory. “There’s eagles all over the place now.”
At one time, there was a single nesting pair in the state, in Salem County. Now there multiple nesting pairs in Cape May County alone, and Crewe said they may be reaching the saturation point, meaning there are about as many eagles around as the ecosystem can support.
A report from the state Department of Environmental Protection states that in 1982, that lone nesting pair of eagles in the state failed to produce an offspring for six years in a row, which officials blamed on residual contamination from DDT.
Last year, 119 eagle nests produced young, with 165 of the eaglets successfully fledging.
The numbers increase in the spring and fall migration periods, when large numbers of birds, including many kinds of birds of prey, make their way through the Jersey Cape. But there are also more birds making their home here – so many that Crewe said they are pestering the osprey south of the Cape May Canal, stealing the fish from the smaller hawks because it is easier than catching their own.
Ben Franklin reported similar behavior, citing it in a letter to his daughter as one reason he didn’t think the eagle should be on the national seal.
“The top predators are always an indication of the health of the environment as a whole,” said Crewe. If eagles are thriving, that’s a good indication that the whole ecosystem is clean.
Crewe, and numerous other sources, date the start of the eagle’s comeback to 1972, when the use of the insecticide DDT was banned in the United States for agricultural use.
The chemical would remain in the fatty tissue of animals, building up over time. And what’s more, it would be passed on to a predator that ate the smaller animals, giving the predator a helping of DDT with each meal.
So if a minnow got a little DDT, it might not be so bad, but if a slightly bigger fish ate 10 minnows, and then something else ate 10 of the slightly bigger fish, the amount of contamination could add up pretty quickly.
For an apex predator like an eagle, those doses added up in a process called biological magnification. Because eagles eat a lot of fish, they would get the DDT not just from each striped bass or drumfish, but from every meal that fish ate, and from every meal its meal had, and so on down the chain.
The chemical wasn’t enough to kill the eagles or even really make them sick. What it did was make the eagle’s eggshells a little thinner.
“It got to the point that it was thinning their eggshells. They were breaking their own eggs when they sat on them. They were not having any young, and the species were just disappearing,” said Crewe.
The same thing happened to osprey and other birds. By the late 1980s, it was a big deal to see an osprey. Now you’re likely to see a few every day if you keep your eyes open at the shore.
Back in the ’80s, under the Endangered and Nongame Species Program, biologists actually took an egg from the state’s only eagle nest, replacing it with a fake one and hatched the thin-shelled egg in a lab using lightweight chickens. The young eagle was then returned to the nest to be raised by its parents.
In another program, biologists brought eagles to New Jersey from Canada. That project ran from 1983 until 1990, releasing 60 eagles.
When Ben Franklin was a kid, there were hundreds of thousands of eagles. According to the American Eagle Foundation, by the 1950s, there were 10,000 nesting pairs, and less than 500 nesting pairs in the 1960s.
That wasn’t just from DDT. Many people shot eagles, which were often seen as a threat to chickens and other livestock. Stories persist of eagles taking lambs and other small animals, although Crewe has some doubts.
“There’s always been persecution of anything with a hooked beak,” he said.
He said he saw an old article in a Cape May newspaper calling on neighbors to participate in a hawk shoot. It was considered almost a civic duty to join in.
The first federal protection was on the books by 1918, and the 1940 Bald Eagle Protection Act prohibited trapping and killing the birds.
Eagles are still protected, but they were removed from the federal endangered species list in 2007.
“After nearly disappearing from most of the United States decades ago, the bald eagle is now flourishing across the nation and no longer needs the protection of the Endangered Species Act,” the U.S. Department of the Interior stated at the time.