Bald Eagle Restoration In New York, 1976 To 1989
Flashback to 1976
One pair of bald eagles still nests in New York, but there are no young birds. In fact, year after year eggs are laid in the nest, but they collapse during incubation, their shells thinned by DDT in the parent birds' bodies. At the same time, people who want waterside homes and vacations are moving into once-remote sites that eagles need for nesting and wintering.
Extinction of the majestic raptors seems inevitable. Though DDT is now banned and a three-year-old federal endangered species law prohibits killing or injuring any bald eagle, how will the species recover if eagles can't produce young?
Enter a team of dedicated biologists in New York's new environmental agency, with an untried idea: perhaps if juvenile bald eagles from other states are released in New York, they will return here to breed, just as they would if they hatched in a New York nest.
There are more questions than answers:
- Will the remaining eagle pair rear a young bird that they did not hatch?
- Can young eagles learn to hunt without the example of eagle parents?
- If we start out by feeding the eaglets, will they keep their wild instincts and survive the five years until they can breed?
- Will eagles return to the place where they first fly, even though they were hatched somewhere else?
- Does New York still have DDT-free habitat where eagles can breed successfully?
How the Eagles Returned
Incredibly, DEC obtained resources for an unprecedented project that would answer these questions, and restore the bald eagle to New York. The results have exceeded even the most optimistic expectations - today, more than 80 bald eagle pairs breed successfully in the state and several hundred of the birds winter here.
In 1989, New York's bald eagle restoration program "put itself out of business" by achieving its goal of 10 bald eagle pairs breeding in the state. The program used two techniques: release of young non-native eagles through hacking (hand rearing to independence), and manipulation of the state's only remaining native pair to foster young.
Hacking - The Experimental Phase
In cooperation with Dr. Tom Cade of Cornell University Laboratory of Ornithology, who had experience with hacking other species, DEC staff devised a hacking process for bald eagles. They placed young birds on an artificial nesting platform several weeks before they were ready to fledge (leave the nest). The birds lived in cages until their feathers became fully developed. They were fed and watched over by human caretakers who worked from a blind to ensure that the young eagles retained their fear of humans.
Then the door of the cage was removed so the eaglets, now 12 or 13 weeks old, could test their flight capabilities. Small radio transmitters were temporarily mounted on the birds' backs. This allowed project personnel to monitor the eaglets' well-being during the critical first few weeks following release. Permanent wing markers would identify each bird for continued observation.
Montezuma Wildlife Refuge in central New York, a former bald eagle nesting area that was found to be free of DDT, became the site of the world's first bald eagle hacking tower. During the five-year initial phase of the restoration program, DEC cooperated with the US Fish and Wildlife Service and Cornell University to successfully release 23 young bald eagles. The four or five eagles released each year during the first five years of New York's program were supplied by the states of Michigan, Minnesota and Wisconsin, and the US Fish and Wildlife Service captive breeding facility at Patuxent, Maryland.
The eaglets did learn to hunt and feed on their own, without the guidance of parent birds. They survived in the wild, and returned to the release site in subsequent years. And in 1980 the answer came to a key question: the first two eagles released at Montezuma in 1976 were found nesting in northern New York near Watertown. In their very first attempt, they hatched two chicks and fledged one.
Remote video observation of New York's only surviving bald eagle pair showed that the birds were carrying out all the functions of nesting, but their eggs broke before they could hatch. Since it appeared that this pair would be good parents, DEC bald eagle program personnel devised a plan to give them a chance.
Within two weeks of the birds settling into incubation, a biologist climbed to the nest, removed any egg present and inserted a plaster dummy egg. The adult birds incubated the artificial egg as their own for the next two to four weeks. Meanwhile, project personnel obtained a bald eagle chick from a captive breeding facility, brought it to New York and "transplanted" it into the nest. For three years, this pair accepted, cared for and fledged captive-bred chicks.
After the male of the original pair died, the female mated with a hacked bird. They returned to the nest site and fostered five more chicks in subsequent years. Since then, hacked eagles have occupied the nest, continuing use of the territory for breeding.
Phase Two - Large-scale Hacking
Having proven that bald eagles could be hacked successfully, the DEC program set a goal of using the technique to restore 10 nesting pairs to New York. The US Fish and Wildlife service approved a plan to obtain about 20 young bald eagles per year from Alaska, where uncontaminated expanses of wilderness supported a thriving eagle population.
Three condominium-style hacking towers were constructed in promising New York habitats, providing rearing space for 175 birds over the next nine years. (Altogether, the bald eagle restoration program released 198 nestling eagles.) As the hacked eagles returned to nest in New York, monitoring and managing the nests and keeping track of the growing population of wintering eagles became a priority for DEC's bald eagle program.
Since the bald eagle restoration program ended in 1989, New York's eagle population has continued to grow, with birds again nesting and wintering in traditional areas and taking advantage of open lands and habitats acquired with funding from the state Environmental Quality Bond Act and Environmental Protection Fund.