Umbagog National Wildlife Refuge
Northeast Region
 
P.O. Box 240
2756 Dam Road
Errol, NH 03579
(603) 482-3415

Bald Eagles of the Umbagog Area

Updated November, 2006

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 to fewer than 450. Various threats contributed to the decline of the bald eagle, including habitat destruction, illegal shooting, lead poisoning and DDT poisoning.

Banded eagles in their nest. Credit: Bill Hanson/FPLE/USFWS
  Banded eagles in their nest. Credit: Ian Drew/USFWS

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 and a clutch of 1-3 eggs is typically laid. Both male and female eagles share incubation of the eggs,which begins as soon as the first egg is laid. 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, but recovery has been successful. 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

Throughout the 1980's Massachusetts and New York released dozens of young, transplanted eagles into the wild (Martin, 2001). One male, released in New York in 1984, made his way to Umbagog Lake and in 1989 began nesting with a female eagle at Leonard Pond, at the north end of Umbagog Lake. This was the first bald eagle nest discovered in New Hampshire in 40 years, and it was built in the very same tree that held the last successful nest in 1949.

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 we anxiously awaited the results. The experiment worked and the eagles accepted and successfully raised the foster chick. During the next breeding season the adults fledged two young of their own.

The Leonard Pond territory has remained continuously active since 1989. Between1989 and 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 through 2005, a new, unbanded pair occupied the territory but failed to successfully hatch any chicks. However, in 2006 the nest was successful and three healthy chicks were fledged.

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 in Sweat Meadow, and in 2007 a nest was discovered in Rapid River.

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 the NH Audbon web site.

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)

Bald eagle in flight. Credit: Doug Alcorn
Bald eagle in flight. Credit: Doug Alcorn  

How to Identify a Bald Eagle

Length: 29 - 35 inches
Weight: 7 - 14 pounds
Wing Span: 7 feet
Immature bald eagles: During it's second and third year, a bald eagle will have mottled brown and white feathers under its wings and on its head, tail, back and breast. In it's third year, a bald eagle often has a dark eye stripe.
Mature bald eagles: At 4 - 5 years of age, bald eagles become mature and develop the distinguishing characteristics of dark brown body feathers, white head and tail and yellow eyes, feet and beak. Females are larger than males.

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

Size: Osprey are smaller with an average wingspan of about 5 feet.
Feet: Juvenile and adult ospreys have gray feet. Juvenile and adult bald eagles and golden eagles have yellow feet.
Wings in flight: In flight, a bald eagle's wings are broad and spread straight out. An osprey's long narrow wings are always angled and bowed down.
Underwing: Ospreys have a distinctive underwing pattern consisting of an all-white belly (buffy-white if juvenile), and an all-white section on the fore-wings. The rest of the underwings are mottled. A mature bald eagle has an all dark brown underwing. An immature bald eagle has a mottled brown and white underwing.
Head: The head of an osprey is mostly white with a distinctive dark eye stripe. A third year bald eagle also has a dark eye stripe, but can be distinguished from an osprey by its mottled appearance, yellow feet and a beak that is beginning to become yellow.

Juvenile bald eagles are sometimes confused with golden eagles.

The main differences between juvenile bald eagles and golden eagles are

Head: Golden eagles have a distinctive golden head and nape. Juvenile bald eagles have a dark brown or mottled brown and white head and nape. Golden eagles also have a smaller head and beak than bald eagles.
Body: Golden eagles have a dark body. Juvenile bald eagles have a mottled brown and white body. Some juvenile golden eagles have all-white patches on their wings, but they are not mottled like juvenile bald eagles.

Bald Eagles of New Hampshire, written by Katie Maguire, 7/01/2001.
Revised 11/2006

For more information, please contact

Lake Umbagog National Wildlife Refuge.
P.O. Box 240
Errol, NH 03579
603-482-3415
lakeumbagog@fws.gov

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.


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Last updated: November 24, 2009