Lake Umbagog
National Wildlife Refuge
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Lake Umbagog National Wildlife Refuge |
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Bald Eagles
Photo of bald eagle: USFWS image DDT, a pesticide widely used after WWII, had devastating effects on eagles and other birds of prey. DDT was sprayed on croplands throughout the country. Its residues washed into lakes and streams contaminating the aquatic plants and small animals. The biomagnification of DDT through the food chain resulted in large pesticide accumulations in bald eagles. The chemical caused the eagles to lay eggs with weak shells, which often broke during incubation or failed to hatch. Not able to produce young, bald eagle numbers plummeted. Eventually people realized the effects DDT was having on the environment. DDT was banned for most uses in the U.S. in 1972, and many efforts were made to help birds that suffered from its use. Due to its declining numbers, the bald eagle was federally listed as endangered in the continental United States in 1967. In 1995, substantial recovery of the eagle population led to reclassification of eagles from endangered to threatened on the federal endangered species list. Bald eagles have since been proposed for complete delisting. Diet: The bald eagle's diet consists mainly of living and dead fish, but they will eat almost anything, including mammals, birds, reptiles and amphibians. (U.S. Fish and Wildlife Service) Raising Young: Bald eagles mate for life and build massive stick nests lined with grasses. The nests are usually constructed in large trees near lakes and rivers or along the coast and other wetland areas. (U.S. Department of the Interior, U.S. Fish and Wildlife Service, 1994) Eagles are sexually mature at the age of four and capable of breeding annually from then on. Some eagles do not breed every year. This may be related to weather, and the availability of food and nesting sites. (Rutledge, 1996-2000) Copulation occurs in February and March. A clutch of 1-3 eggs is typically laid. Incubation of the eggs begins as soon as the first egg is laid. Both male and female share incubation of the eggs. The incubation period lasts approximately 35 days. In the Umbagog area, eagle chicks generally hatch before mid-May. The chicks stay in the nest for 11-12 weeks, and fledge the nest in late July or early August. Eagles become very territorial during breeding season. There is always one eagle incubating the eggs while the other is perched on a nearby branch or soaring above the nest to protect against predators. It is important not to disturb nesting eagles. When they are approached too closely, they may leave the nest, exposing the eggs or young to predation. Eagle nesting areas on the Refuge are marked with float lines or signs warning people to stay back. Bald Eagles in Maine: Maine, with a large coastline, provides more suitable habitat for eagles than New Hampshire and thus bald eagles are more common in Maine. The use of DDT and lead shot had devastating affects on the eagles in Maine. Maine's eagle population declined to fewer than 30 pairs in the early 1970's. Eagle recovery has been successful in Maine. In 2005, there were more than 370 pairs in the state ( Maine Department of Inland Fisheries and Wildlife). Bald Eagles in New Hampshire: The bald eagle is still uncommon throughout New Hampshire. In 2006, the state had only 12 active nests sites (New Hampshire Audubon). The bald eagle was first placed on the New Hampshire threatened and endangered species list as an endangered species in 1979. At that time there had not been eagles nesting in the state in of New Hampshire for 30 years. (Martin, 2001). The eagle territories on
Umbagog Lake: Initially, the eagles behaved as though they had young and biologists assumed there were one or more chicks in the nest. Then suddenly the behavior of the eagles changed, and it became clear that the chick(s) had not survived. Working quickly, biologists found a captive-raised chick to put in the nest. Placing a foster chick into a nest that already has a chick is not that uncommon. However, placing a foster chick into an empty nest was unusual and everyone watched to see what would happen. The experiment worked and the eagles accepted and successfully raised the foster chick. The next breeding season the two adults fledged two young of their own. The Leonard Pond territory has remained continuously active since 1989. Between1989-2001 the nest produced 16 young (including two foster chicks). The original banded female paired with several different males during that time. The original male of the pair died from suspected lead poisoning in 1994, and the female immediately paired with a second male. That second male disappeared after 1999 and the female paired with a new male. 2001 marks the last year that the original banded female (then 16 years old) was confirmed to have nested at Leonard Pond. In 2002, an unidentified pair of eagles occupied the Leonard Pond territory, but failed to lay any eggs. During 2003-2005 a new, unbanded pair occupied the territory but failed to successfully hatch a Since the first eagle pair nested at Leonard Pond in 1989, two other nesting eagle territories have been established in the vicinity of Umbagog Lake. One of these, located east of the Lake, has successfully fledged chicks each year since it was first observed in 2000. In 2005 a third eagle territory was established, but has failed to successfully produce any young to date. Photo of bald eagle chicks in Leonard Pond nest, 1992, Mike Amaral. Other nests in the state of NH: In recent years, additional nesting territories have been established elsewhere in New Hampshire, beyond the Umbagog area. In 2006, there were 12 territorial pairs of eagles in New Hampshire (including the 3 pairs at Umbagog), that produced a total of 21 chicks. More information about eagles in New Hampshire may be found at: www.nhaudubon.org Photo of banding a bald eagle chick at Tidswell Point , 2000 : USFWS image Bald eagles in New Hampshire are monitored by the New Hampshire Fish and Game's Nongame and Endangered Wildlife Program, the Audubon Society of New Hampshire and the U.S. Fish and Wildlife Service, with cooperation from landowners, volunteers, and local conservation organizations. (Martin, 1999) How to Identify a Bald Eagle: Bald eagle, golden eagle or osprey? In the Umbagog area there are many ospreys as well as bald eagles. Golden eagles do not currently nest near the Refuge and are rarely seen in the area. There are several ways to distinguish
a bald eagle from an osprey:
Bald Eagles of New Hampshire, written by Katie
Maguire, 7/01/2001. For more information, please contact the Lake Umbagog National Wildlife Refuge. P.O. Box 240 Works cited: Martin, Chris. 2001. New Hampshire Audubon. The American Bald Eagle (Haliaeetus leucocephalus) Martin, Chris. 1999. New Hampshire Fish and Game Department News and Information. Peterson, Roger T. (1980). Peterson Field Guides: Eastern Birds. Houghton Mifflin Company. Unknown Author. U.S. Fish and Wildlife Service.1994. Eagle. Maine Department of Inland Fisheries and Wildlife. 1998. Bald Eagle.
http://www.state.me.us/ifw/
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History: Wildlife
experts believe there may have been 25,000 to
75,000 nesting bald eagles in the lower 48 states when the bald eagle was
adopted as our national symbol in 1782. By the 1960s that number had
dropped significantly to fewer than 450. Various threats contributed to
the decline of the bald eagle, including habitat destruction, illegal shooting, lead poisoning and DDT
poisoning.
