Monday, June 8, 2009

Peregrine Falcons

I recently read online that the peregrine falcon is being removed from Iowa's endangered species list and it sent me back to check on the speies status in NJ.

Peregrine falcons (Falco peregrinus) are sometimes called an "indicator" species because they begin to vanish when pollution, over-hunting and other environmental factors encroach, an indicator of serious problems.

When the chemical DDT was widely used as a pesticide years ago, it turned out to be killing more than just bugs. Peregrines were nearly wiped out by DDT. The federal list was created in 1972 when DDT was banned nationwide and the Endangered Species Act was implemented.

Peregrine falcons were removed from the federal list in 1998, but remain on NJ's endangered species list.

Peregrine falcons are amazing. Like all falcon species, they are designed for speed. In a dive, peregrines can reach speeds of up to 200 M.P.H., making it the planet's fastest bird.

Traditionally, peregrine falcon nest sites were restricted to cliffs and rock outcrops, but as people began to inhabit areas occupied by peregrines, the birds took to nesting on buildings and bridges. In NJ, they continue to nest on these structures. There are no remaining cliff nests on the Hudson Palisades or the Delaware River in New Jersey. NJDEP has also built artificial nesting platforms in coastal marshes which are still active today.

It seems hard to believe today, but into the 1950s, egg collectors and falconers looted peregrine nests, while gunners, game wardens, and pigeon fanciers shot adult falcons, which were viewed as vermin.

DDT was heavily used in NJ for mosquito control and had a devastating effect on population declines for the peregrine falcon, osprey and bald eagle. Because these predators are high on the food chain, DDT had accumulated at levels that inhibited calcium metabolism which caused eggshell thinning in the birds. The resulting eggs cracked under the weight of the incubating adult.

By the 1960s, they were extirpated - there were no known nesting peregrines in the East.

DDT was banned in New Jersey in 1968 and in the United States in 1972. The peregrine falcon was classified as a federally endangered species in 1970 and as a New Jersey endangered species in 1974.

NJ biologists released young peregrines into the wild during the latter half of the 70s. This "hacking" was intended to reestablish nesting populations. Peregrines often return to their birth sites to breed.

The first releases in the traditional cliff sites unfortunately experienced high mortality due to great horned owl predation. The coastal man-made nesting structures were in locations where owl numbers were lower and prey was abundant.

The first nest site was at the Edwin B. Forsythe National Wildlife Refuge in Atlantic County. An analysis of eggshells from NJ nests still contained residual contaminants during the early 1980s, but were low enough that they shouldn't have impaired reproduction.

The peregrine had reached its NJ recovery goal of 10 pairs by 1986, and had stabilized at that level through the early 1990s.

Owl predation continued to be a problem for nests along the Delaware Bay and River. Unhatched eggs there and in the Barnegat and Manahawkin bays may have been a result of PCB contamination as well as DDE, chlordane, and dieldrin in the early 1990s.

Currently, the state’s peregrine population remains stable at about 15 pairs and exhibit good productivity, averaging 1.7 young per nest on buildings and towers since 1986.

Though the peregrine falcon was removed from the federal endangered species list in 1999, they continue to be listed as endangered in New Jersey because they remain threatened by environmental contaminants and human disturbance, and rely on active management of their nesting sites.

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