The Central Sierra Audubon Society counted 68 bald eagles at the reservoir during its 2012 Christmas Bird Count, which is 63 more than the previous year, according to event organizer Barry Boulton.
“It’s amazing,” New Melones Park Ranger Hilary Maxworthy said. “I’ve never seen anything like it.”
The Audubon Society and New Melones Reservoir representatives said eagles have been gathering near the Camp 9 Bridge on the middle fork of the Stanislaus River, where kokanee salmon have been spawning.
Kokanee typically spawn from August to early December, moving into inlet streams of lakes and along shores. They leave behind carcasses for the scavenging bald eagles to feed on, Maxworthy said.
The influx of bald eagles in the Mother Lode this year reflects the species’ recovery nationwide.
Bald eagle populations in the United States have slowly rebounded since reaching an all-time low in 1963, when only 417 breeding pairs were known in the lower 48 states, according to the U.S. Fish and Wildlife Service.
By 2011, the population had grown to nearly 10,000 pairs in the contiguous states. Bald eagles do not live in Hawaii and have thrived in Alaska.
When the U.S. adopted the bald eagle as a national symbol in 1782, there were as many as 100,000 nesting eagles, the service said.
It estimated the species experienced its first major decline in the mid-to late 1800s, coinciding with the dwindling of waterfowl, shorebirds and other prey.
While eagles primarily eat fish and carrion, they have preyed on chickens, lambs and other domestic livestock. Farmers, ranchers and other people began shooting bald eagles to protect farm animals.
In 1940, Congress passed the Bald Eagle Protection Act, which prohibits killing, selling and possessing bald eagles.
Bald eagles continued to suffer after World War II, when the use of DDT pesticides on crops became widespread in the U.S.
The pesticide washed into waterways, contaminating fish and the birds who ate them. Bald eagles that consumed the pesticide were unable to produce strong egg shells, and their offspring failed to hatch, according to the service.
The eagles were listed as an endangered species in most U.S. states in 1978. The phase out of DDT spurred a recovery.
The bird was considered a “threatened” species — no longer “endangered” — in July 1995 until June 2007, when its recovery was officially announced.
The bald eagle is still protected by the Migratory Bird Treaty Act and Bald and Golden Eagle Protection Act, which prohibit the killing, selling or otherwise harming of bald and golden eagles, their nests and their eggs.