Maine’s Bald Eagle Recovery

In 1962, after years of population declines, National Audubon Society biologists (Charles Brookfield, Frank Ligas and Sandy Sprunt) began annual monitoring of Bald Eagle nests reported in Maine, as well as limited searches for additional locations. 

The effort lacked the resources to identify all nests. However, it established a baseline of recently used nest locations that would be monitored through the years, serving as an indicator of further population declines yet to come, and (decades later) the eventual population recovery that would follow. 

Only 27 nesting pairs were found across Maine during 1962. Eagles were absent in seven counties, but remnant numbers were found in the remaining nine counties. As an indicator that the population was still trending downward, eagles would occupy only four of these 27 territories steadily through the 1960s. Three were in coastal Washington County which would emerge as the last stronghold for Maine eagles during the 1970s.

In 1967, Bald Eagles became listed as "Endangered" in states south of the 40th parallel under the Endangered Species Preservation Act enacted in 1966. In this same year, Maine reached what would become the official lowest count of Bald Eagles, with only 21 nesting pairs. Furthermore, eagle reproduction in Maine was 60-70% below normal rates in this period. Only 6 young eaglets survived at Maine nests in 1967. 

Starting in 1972, wildlife agencies used aerial surveys to locate Bald Eagle nests in Maine and monitor breeding success. Finding nests in remote areas was a key advantage, but all methods revealed frequent nest failures and eventual abandonment of many traditional eagle habitats.

One of the main factors contributing to the decline of Bald Eagle populations was environmental contaminants. By-products of the insecticide DDT, a complex family of industrial pollutants known as PCBs, similar organochlorine compounds, mercury and its metabolites, and lead were most influential. DDE is a metabolite of DDT that caused widespread breeding failure due to shell thinning in eggs, causing the eggs to break during incubation. Poor breeding success, widespread declines, and the eventual recovery of eagles were correlated with the rise and drop-off of DDE levels. DDT was banned in 1972, but DDE residues still persist (albeit at lower parts per million) in Maine eagles.Other contaminants featured in the map can either impair embryo development in the egg or act as a neurotoxin to older eagles. Dioxin and some PCBs are detrimental at a trace exposure level measured in "parts per trillion". Most of these contaminants circulate widely as air pollution but reach eagles via complex aquatic food chains. Several risk factors made Maine's eagles especially vulnerable:

1. Maine is downwind from industrial regions of the U.S. and more vulnerable to atmospheric pollutants
2. Maine's relatively cold climate, short growing season, and acidic soils greatly prolong the longevity of persistent contaminants
3. Eagles in Maine often eat seabirds, waterfowl and wading birds. All are higher in the food chain and carry higher pesticide residues of these contaminants than fish

The map to the right shows the locations of samples with alarmingly high levels of one or more contaminants in addled eagle eggs, tissue samples from deceased eagles, or blood samples from live eagles detected during various studies in Maine. Click on a location to see the measured levels and further information about the sample. Click on the box in the lower left to expand the map legend.

For further information on contaminants in Bald Eagles in Maine, see these  study citations .

Eagles would disappear in all but one territory in the western half of Maine’s coastline that once boasted exceptional eagle abundance. That location on the  Swan Island Wildlife Management Area  owned by the Maine Department of Inland Fisheries and Wildlife (MDIFW) was never abandoned despite the loss of all other pairs from the lower Kennebec River estuary, the mid-coast region, and Penobscot Bay. 

When first found in 1964, the "Great Nest" as it was called, measured 20 feet vertically, and biologists conservatively estimated that it had been in use for about 60 years! Despite eagle loyalty to this nest, no eaglets fledged here during 1964 - 1988. However, from 1989 - 2013, 29 eagles fledged from this nest! The enormous nest pictured on the right is only 7 feet tall!!

The Maine Department of Inland Fisheries and Wildlife used a number of strategies to assist the population growth of Bald Eagles in Maine. These strategies included direct intervention to increase productivity and survival, as well as habitat conservation.  

Extraordinary measures were attempted to offset very low productivity and pending regional extirpation of eagles in western Maine. Addled, native eggs were replaced by eggs (1974 - 1976) or eaglets (1975, 1979, and 1981) from captive-breeding or donor populations. This enhanced the local supply of eaglets and potential recruitment in order to avoid more costly, uncertain management such as re-introductions of the species after local extirpation.

At right: U.S. Fish and Wildlife Service (USFWS) biologists Paul Nickerson and Frank Gramlich replace addled eggs at an eagle nest in the Kennebec valley with donor eggs from Wisconsin.

Bald Eagles often exhibit extreme loyalty over years or decades to an individual nest. If a nest is destroyed, eagles typically build a replacement nearby. This “site fidelity” was used in efforts to safeguard and recover eagle populations. For more than 40 years, MDIFW and partners used one or more of three key strategies: 

First, agencies negotiated voluntary Cooperative Management Agreements with landowners to protect the few active eagle nests remaining in Maine. The U.S. Fish and Wildlife Service prescribed 660-foot buffers (~31 acres) around active eagle nests starting in 1972. In 1983, MDIFW expanded buffers to a 1320-foot radius (125 acres) for both occupied and intact alternate nests. More than 80 locations benefited. 

*Click on a nest to see further information about the Cooperative Management Agreement 

In the late-1980s, new nests were increasingly found in areas subject to land use changes which could either cause breeding failure or nest abandonment. Inconsistency in the regulatory process led to the issues moving into the courts. The Legislature amended Maine’s Endangered Species Act to enable MDIFW to map “Essential Habitats” for listed species by rulemaking. The designation enabled MDIFW to provide oversight of projects permitted, licensed, funded, or carried out by municipalities and state agencies. The Essential Habitats followed the expanding population and shifting nest locations. After a 5-year absence of eagles, an Essential Habitat designation was removed. During 1990 – 2009, a total of 805 nest locations were well-protected by the rule. More than 99% of project applications were approved AFTER adjustments to safeguard the eagle nesting season and key habitat components.   Click here  to see an example of an official Essential Habitat map. 

*Zoom in and Click on nest site to see further information on the Essential Habitat 

In 1995, Bald Eagles were "downlisted" under the federal Endangered Species Act to "Threatened" status in all 48 conterminous states, including Maine. 

By this point in time, Maine's population had increased to 192 nesting pairs.

Changes in mortality rates are the biggest influence on eagle population stability. Mortalities attributed to human influences (illegal shooting, impacts with vehicles or utility lines, poisonings, entanglements, etc.) are typically additive to the natural death rates of long-lived species, such as Bald Eagles. Wildlife rehabilitation can play a role in reducing these mortalities and in returning sick or injured birds back into the wild. Maine is lucky to have several outstanding wildlife rehabilitation facilities.  Not only do these facilities help injured birds, but they provide educational opportunities for the public on issues facing wildlife and how we can reduce mortalities and injuries due to human influence. A great example is making sportsmen/women aware of effective and affordable alternatives to lead ammunition.  

The eagle on the left was admitted to  Avian Haven  from Industry on July 18, 2017, and the eagle on the right was admitted from Brunswick on August 27, 2017. Both of them were released on September 28, 2017 at Benton Falls. Since opening for business, Avian Haven has admitted 330 eagles (through June 2019).  Most are returned to the wild after treatment and flight conditioning.

Although the Bald Eagle no longer receives protection under the Endangered Species Act (ESA), it continues to receive protection under the Bald and Golden Eagle Protection Act, the Migratory Bird Treaty Act, and the Lacey Act. All prohibit “take,” which is defined as possession, transport, export, import, purchase, sale, trade, or offer to exchange eagles, parts thereof, eggs, or nests. 

The Bald and Golden Eagle Protection Act is the primary protection tool now that the Bald Eagle is federally delisted. For details of how this act is applied, go the following USFWS website:   https://www.fws.gov/law/bald-and-golden-eagle-protection-act 

By 2009, Maine's Bald Eagle population had recovered to approximately 503 nesting pairs. Maine’s population recovery rate of 8% average annual growth since 1990 was moderate, compared to some other states. The range of Bald Eagles gradually expanded from easternmost Washington County, which was the only stronghold 30 years ago. Eagles now resided in all sixteen Maine counties, but 58% of the population still nested in three Downeast counties: Hancock, Penobscot, and Washington. 

In January of 2009, the Commissioner of the Maine Department of Inland Fisheries and Wildlife recommended the removal of the species from Maine's Endangered and Threatened Species List after all state  criteria  for recovery were achieved. The Federal Government had previously removed Bald Eagles from the Endangered and Threatened Species List in 2007, however, federal delisting does not automatically trigger state delisting in Maine. To remove the Bald Eagle from Maine’s list, the Commissioner of MDIFW must recommend its removal to Maine’s Legislature, who has the final authority for listing and delisting.

 Delisting of Bald Eagles in Maine  did not remove all state protections for the species. Two Maine statutes prohibit hunting, possession, and destruction of nests or eggs: a  2009 revision  to the Maine Endangered Species Act and traditional protection of all non-game birds and their nests.

When eagles were removed from the State list of endangered and threatened species, the Essential Habitat rule ended. However, agencies and conservation partners had long before begun a third strategy to conserve some eagle nests by land acquisitions or easements. Maine is blessed with citizens who value our special natural resources and a network of effective conservation partners that work locally, statewide, regionally or nationally. When this effort started, only 5% of Maine’s eagle nests were permanently protected. In contrast, now …

• 40% of all nest locations documented during 1962 – 2018 are on conservation land.
• 55% of all nests benefit from land conservation in the primary nest buffer (< 1,320 feet).
• 85% benefit from lands within 1 mile (within the core home range of nesting eagles) that will retain their character forever!
• Ten organizations working statewide hold lands or easements within 1 mile at 67% of all eagle nests documented in Maine since 1962:   Maine Department of Inland Fisheries and Wildlife,   Maine Bureau of Parks and Lands ,  U. S. Fish and Wildlife Service ,  National Park Service ,  Penobscot Nation ,  Passamaquoddy Nation ,  Maine Coast Heritage Trust ,  The Nature Conservancy ,  New England Forestry Foundation , and  Forest Society of Maine .
• At least 114 towns and cities along with 67 local/regional land trusts also hold lands or easements within 1 mile of eagle nests in Maine.

*Zoom in to an area and then Click on a nest to see further information about the conservation lands that are helping to preserve the traditional eagle nesting habitat

Banded on a nest on  Grand Manan Island  in New Brunswick by MDIFW Biologist Charlie Todd on June 21, 1983, this bird was found injured near  Haycock Harbor  (about 10 miles south of Lubec) on April 7, 2017. Game Warden Joe McBrine and USFWS Biologist Amanda Hardwicke retrieved the eagle, and it was then transported to  Avian Haven  in Freedom. The eagle had lacerations on the left wing and an elevated blood lead level. She also had a puncture wound in her right leg.  

Prior to this, she had last been seen by USFWS Biologist Mark McCollough in  Edmunds Township  in March of 1984.  

Assuming an average hatching date for northeastern Bald Eagles of May 1, she was recovered just a few weeks shy of her 34th birthday, making her the  oldest banded eagle on record with ties to Maine! 

Unfortunately, the bird was not releasable, but she continued to reside at Avian Haven and serve as a surrogate eagle parent for 4 younger eagles who were admitted to the facility. She sadly had to be euthanized in May of 2019 after the inevitability of old age. 

*Click on the map pushpins to see key locations for this bird

 View other longevity records for Maine's Bald Eagles 

Fifty-eight eagles with Maine origins have been observed outside the state: predominantly subadults in New England, New York, and the Chesapeake Bay region. The most distant and rapid dispersal from Maine was a first-year eagle found 900 miles away in South Carolina only 15 weeks after fledging (Todd 1979). One radio-tagged eagle made three round trips between eastern Maine and Connecticut during a 17-week period in its first winter and the following spring (McCollough 1986).

 Todd, C. S. 1979. The ecology of the bald eagle in Maine. MS thesis, Univ. of Maine, Orono. 91pp. 

McCollough, M. A. 1986. The post-fledging ecology and population dynamics of bald eagles in Maine. PhD dissertation, Univ. of Maine, Orono. 106pp.

This eagle was radio-tagged and dispersed from its natal nest near Jay, Maine on August 8, 2013. It arrived in Saint Georges, Quebec (120 miles north) by August 25th. And then kept going! 

He arrived in northern interior Quebec (between Hudson Bay and Ungava Bay), at a location 980 miles from home on September 9, 2013. He left the region in mid-October and showed up near Center Harbor, New Hampshire on November 13th and then spent the winter of 2013-2014 around Lake Winnipesauke, New Hampshire. 

The eagle visited western Maine each spring, but proceeded to cycle between northern Quebec each summer and central New Hampshire each winter during 2014, 2015 and 2016.

 Some further highlights (click on pushpins to see further information): 

March 24, 2017 the eagle was on the Kennebec River in Augusta

May 10, 2017 he was in northern Aroostook County near St. Francis Lake

May 13, 2017 he was along the south shore of the St. Lawrence River east of Quebec City. By May 15, he had travelled 280 miles further NNW to Lac Mistassni, Quebec

August 7, 2017 he was in northern Quebec, west of Ungava Bay (920 miles north of his natal nest)

March 11, 2018 he was back near Meredith, NH at Squam Lake

The last location was on April 11, 2018 along the New Hampshire border near Porter, Maine

This bird was banded and radio-tagged as part of a study by research partners at  Biodiversity Research Institute