The bald eagle, a national symbol of strength and resiliency, may be a common sight today, but just a few decades ago toxic pollutants working their way up the food chain had the species toeing the line of extinction. Prevalent use of dichloro-diphenyl-trichloroethane (DDT), a harmful insecticide, on agricultural fields caused eagles to produce eggs that were too delicate to support the incubating bird, lowering hatch rates in a drastic way. The decline was so severe that by DDT’s ban in 1972, only 482 breeding pairs were left throughout the entire continental United States.
Following the ban, one nesting pair of bald eagles remained in the state of New York, and their eggs were too contaminated with chemicals to be considered a viable means of repopulation. Restoration efforts began across the nation, but two researchers in particular, Peter Nye from the New York Department of Environmental Conservation (DEC) and Tom Cade of Cornell University put New York on the map as a key player in eagle repopulation tactics. They took to using an ancient falconry practice called hacking to raise eaglets in a controlled, but wild, environment, to ensure that the birds would learn the proper survival techniques to independently prosper after fledging the nest.
Wildlife Technician Scott Van Arsdale from DEC keeps a support rope tight as Clark climbs toward a nest holding juvenile bald eagles in a white pine tree near Otsego Lake in Cooperstown, N.Y., on May 27. “Now we have all kinds of fancy GPS transmitters that lessen the need to band eagles,” Van Arsdale said. “With the eagle population coming back so strong, there is less of a need to babysit every individual eagle, and we can actually learn more by transmittering a few birds than tagging a whole bunch.”
“Their goal was to establish 12 nesting pairs in New York. By 1988, they had achieved the goal of 12 nesting pairs, and here we are in 2015 with more than 300. I know down in Maryland in the Chesapeake Bay area there are even more, so the reintroduction has been very successful,” said Michael Clark, Senior Wildlife Biologist for New York DEC. Clark and his colleague Scott Van Arsdale, Wildlife Technician for New York DEC, were mentored by Nye, and have taken over the legwork of tagging and monitoring the birds since Nye’s retirement.
Michael Clark swings a leg up to reach the nest. Bald eagle nests can be used by the same nesting pair of eagles in multiple years and can weigh up to two tons.
A roughly six-week-old male bald eagle awaits a prompt return to its nest after being fitted with a monitoring band.
One of two bald eagle parents circles overhead while researchers band juveniles in the birds’ nest.
Scott Van Arsdale holds a juvenile bald eagle to show its newly received metal band. The bands are color-coded blue for the state of New York, and represent individual birds with a unique three-digit code.
Scott Van Arsdale uses a bag to lift a juvenile bald eagle back to its nest, roughly 90 feet above the ground.
Michael Clark lowers to the ground after successfully tagging the juvenile bald eagles, whose nest is roughly 90 feet above the ground. “Alright, guys. You guys have a good life,” Clark said before his departure.
Michael Clark puts away his climbing gear after finishing with the banding. He wasn’t sure if a a recent injury was going to keep him from climbing that day.
Scott Van Arsdale returns to his vehicle after completing the successful banding. “Banning DDT wasn’t enough because we didn’t have the birds to get the population going, so if you see an eagle in New York, and even Maryland to some extent, you can thank Peter [Nye] because 16 other states and the province of Ontario followed our lead with the hacking program,” Van Arsdale said.
To view more photos, visit the Chesapeake Bay Program’s Flickr page.