Bald Eagle

Environmental Review Fact Sheet Series



Endangered, Threatened, and Special Concern Species of Minnesota


Bald Eagle

(Haliaeetus leucocephalus)

Minnesota Status: Special Concern

State rank1:
S3
Federal Status:
Threatened


Global Rank1: G4





HABITAT
During the breeding season, the Bald Eagle typically inhabits forests near lakes and rivers where large trees are
available for nesting. The nest trees are usually within 1 mile of water, and are often closer. In northern Minnesota,
red or white pines in the supercanopy (taller than the surrounding forest) are often selected as nest trees, whereas in
the central and southern part of the state, eagles choose large hardwoods such as aspen or cottonwood. In winter,
Bald Eagles can be found in upland areas where game or carrion is available. However, it is most common for them
to congregate along major rivers where open water remains (such as near dams or power plants), as these areas
provide opportunities for obtaining their major food items, fish and waterfowl.



LIFE HISTORY
For the purpose of assessing the impacts of human activity on Bald Eagles, the nesting period can be broken into
four segments, as detailed in the following table. The “wintering” season for Bald Eagles varies by latitude, but can
generally be considered to be October 15th through March 15th (a period which includes spring and fall migration).



Dates
for

Nesting Period Segment


Northern Minnesota*
Southern Minnesota*



Critical - Eagles are involved with courtship, egg-laying, and incubation.
March 15th - May 15th
Feb. 10th - May 1st



Moderately critical - Eagles are becoming physiologically conditioned for
Feb. 15th - March 15th
Jan. 10th - Feb. 10th
breeding (February/March), or newly hatched chicks require frequent brooding
and
and
and feeding (May/June).
May 15th - June 15th
May 1st - June 1st



Less critical - Eagle chicks are one month old to 1 week post-fledging.
June 15th - Aug. 15th
June 1st - July 31st



Non-critical - Most eagles are not regularly present at the nest site.
Aug. 15th - Feb. 15th
July 31st - Jan. 10th
*The state is arbitrarily divided into north and south by State Highway 210.



IMPACTS / THREATS / CAUSES OF DECLINE
• habitat loss
• power lines and transmission structures (collisions,
electrocutions)
• human disturbance
• roads and bridges (vehicle collisions)
• farm runoff and industrial pollution
• lead poisoning (e.g. by lead shot ingested by eagles during feeding)
• leg-hold traps
• shooting (in violation of state and federal law)
• management activities such as timber
• contaminants and poisons (particularly organochlorine,
harvest and burning
organophosphorus, mercury and other heavy metals)

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PROTECTION

Bald Eagles are protected under the Migratory Bird Treaty Act, and under the Bald and Golden Eagle Protection Act
of 1940 and the Endangered Species Act of 1973, as amended, which prohibit the possession or taking of Bald
Eagles, or their nests, eggs, or young. “Taking” is defined by the Endangered Species Act as to harass (i.e., create
the likelihood of injury), harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in
any such conduct. Prohibited activities include, for example, cutting down nest trees (at any time of the year), and
intense human activity that is demonstrated to have caused adult eagles to abandon eggs or young in the nest.
Possession permits may be issued by the U.S. Fish & Wildlife Service for Indian religious purposes, or for scientific
or exhibition purposes of public museums, public scientific societies, or public zoological parks.

In addition, the National and Minnesota Environmental Protection Acts prevent certain actions which would cause
significant adverse impacts to the environment (including destruction of habitat for listed species) if there is a
reasonable alternative to the proposed action.

If you are uncertain whether a proposed action may take Bald Eagles or their nests, or if you for any reason cannot
follow the recommendations below, contact USFWS Ecological Services at (612) 725-3548.



RECOMMENDATIONS FOR AVOIDING AND MINIMIZING IMPACTS

These recommendations will be useful in avoiding or minimizing effects that may be caused by federal or non-
federal actions, but all federal actions that may affect bald eagles must also complete consultation with U.S.
Fish and Wildlife Service under section 7 of the Endangered Species Act. A federal action is any action that a
federal agency funds, authorizes, or carries out. Contact the U.S. Fish and Wildlife Service at (612) 725-3548 for
further information regarding section 7 consultation.


WINTERING AREAS2
Bald Eagle wintering area habitat contains three main components: foraging (feeding) areas, daytime perching areas,
and night roosts. Within these areas, eagles need to be protected from human disturbance, physical alterations of
their habitat, environmental contaminants, and loss of food resources.

Foraging and Daytime Perching Areas: In Minnesota, winter foraging areas where Bald Eagles congregate are
located primarily along major rivers. Daytime perches tend to be near these foraging areas. While eagles are
present, buffer zones (areas within which there is no human activity) of at least 1/4 mile (400m) should be
maintained around foraging areas where possible. Where this is impractical, human use should be avoided between
sunrise and 10am, when Bald Eagle feeding activity is greatest. Buffer zones around daytime perches should be 1/8
to 1/4 mile (250m-400m). At foraging areas along rivers, trees within 100 ft. of the shore seem to be preferred as
perches. Therefore, no trees greater than 12 in. diameter should be removed within 100 ft. (33m) of river banks or
other foraging areas. Activities which have the potential to kill trees (such as livestock grazing and dumping of
dredge spoil) should be avoided within foraging and perching areas. New road and bridge construction should be at
least 1/2 mile from major foraging areas.

Night Roosts: Bald Eagles are more sensitive to disturbance at night roosts than at foraging and daytime perching
areas. No logging, development, or road building should occur at any time in critical roosts. Critical roosts are
defined as those used more than 14 nights per season by eagles from local breeding territories or more than 14 nights
per season by more than 15 eagles or roosts which have been documented as active for 5 years or longer. A buffer
zone of at least 1/4 mile (400m) should be maintained around night roosts, within which both low and high impact
activities, including recreation, are restricted while the roost is in use. New road or bridge construction should be at
least 1/5 mile from critical roosts.

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RECOMMENDATIONS FOR AVOIDING AND MINIMIZING IMPACTS Cont.

NESTING AREAS
Studies show that Bald Eagles are vulnerable to human intrusion. The vulnerability varies with the type of
disturbance and the particular eagle, as some individuals have become accustomed to human activity near their nests.
However, because some eagles are easily disturbed, human contact with Bald Eagles should be avoided whenever
possible, particularly during the critical segment of the nesting period. The following table, adapted from the
Minnesota Department of Natural Resources (DNR) Management Guidelines for Bald Eagle Breeding Areas, and the
Northern States Bald Eagle Recovery Plan, summarizes recommendations for protecting individual occupied and
active nest sites.

If a nest is not occupied during the year in which the activity will occur, the recommendations for the Non-critical
Nesting Period Segment may be used year-round. If a nest is abandoned (unused for more than 5 years and not
being maintained by eagles), activities are only restricted within the Primary Zone. Whether a nest is occupied,
unoccupied, or abandoned must be determined in consultation with a DNR Nongame Specialist (see contact numbers
below the table) and the U.S. Fish and Wildlife Service (612-725-3548). Because eagles often rebuild nests that
have been blown out of trees, in this situation activities are restricted within the Primary Zone for 3 years after the
event. If the nest is not rebuilt, zone restrictions are removed.

Activity
Nesting Period Segment
Critical
Moderately
Less Critical
Non-critical
Primary Zone: (within 330 feet of the nest)
Landscape Alterationa
avoid avoid avoid
avoidb
Construction (structures, trails, etc.)c
avoid avoid avoid
avoidb
Burningd
avoid avoid avoid
restrict/minimizeb
Minor Forest Maintenancee
avoid avoid avoid
restrict/minimizeb
Motorized Access
avoidf avoidf restrict/minimizeb restrict/minimizeb
Human Entry
avoidf avoidf restrict/minimizeb restrict/minimizeb
Low Flying Aircraft
avoid avoid no
restrictions no
restrictions
Secondary Zone: (330 to 660 feet from the nest)
Landscape Alterationa
avoid avoid avoid
restrict/minimizeb
Construction (structures, trails, etc.)
avoid avoid restrict/minimizeb restrict/minimizeb
Burningd
avoid avoid avoid
restrict/minimizeb
Minor Forest Maintenance
avoid avoid no
restrictionsf no
restrictionsg
Motorized Access
avoidf restrict/minimizeb restrict/minimizeb no
restrictionsg
Human Entry
avoidf restrict/minimizeb restrict/minimizeb no
restrictions
Low Flying Aircraft
avoid restrict/minimizeb
no restrictions
no restrictions
Tertiary Zone: (660 feet to 1/4 mile from the nest - May extend up to 2 mile from the nest, if topography or vegetation permit a
direct line of sight to the disturbance area.)
Landscape Alterationa
avoid avoid avoid
no
restrictionsg
Burningd
avoid avoid avoid
restrict/minimizeb
Other Activities (as listed above)
avoidf no
restrictionsg no
restrictionsg no
restrictionsg

a Landscape alteration includes activities such as clear cutting or land clearing, which result in significant changes in the landscape.
b Restrictions should be decided on a case by case basis, based on type, extent, and duration of proposed activity, and sensitivity of
individual eagle pairs. For assistance, contact your nearest DNR Nongame Specialist: Bemidji (218-755-2976); Grand Rapids (218-
327-4267); New Ulm (507-359-6033); Rochester (507-280-5070); St. Paul (651-772-7978).
c For construction involving land clearing, see also recommendations for the “Landscape Alteration” activity.
d If burning can not be done within the non-critical nesting period segment, please contact your nearest DNR Nongame Specialist (see
contact numbers above).
e Such as thinning of tree stands, pruning, and other like maintenance.
f Some eagles have become habituated to human activity and can be tolerant of these activities, particularly if they were occurring
regularly at the time the eagles began nesting. In these cases, complete avoidance of the activity may not be necessary. If you believe
this is the case in your particular situation, contact your nearest Nongame Specialist (see contact numbers above).
g However, the habitat should not be altered in ways that would make it unsuitable for future nesting.


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REFERENCES
1Association for Biodiversity Information. “Heritage Status: Global, National, and Subnational Conservation
Status Ranks.” NatureServe. Version 1.3 (9 April 2001). http://www.natureserve.org/ranking.htm (15
April 2001).
Coffin, B., and L. Pfannmuller. 1988. Minnesota’s Endangered Flora and Fauna. University of Minnesota
Press, Minneapolis, 473 pp.
Grier, J. W., J. B. Elder, F. J. Gramlich, N. F. Green, J. V. Kussman, J. E. Mathisen, and J. P. Mattsson. 1983.
Northern States Bald Eagle Recovery Plan. U. S. Fish and Wildlife Service. 76 pages +appendices.
2Martell, M. 1992. Bald Eagle Winter Management Guidelines. Unpublished brochure, The Raptor Center,
University of Minnesota, St. Paul, unpaged. August.












































Compiled by the Minnesota Department of Natural Resources Natural Heritage and Nongame Research Program, June, 2003

Endangered Species Environmental Review Coordinator, 500 Lafayette Rd., Box 25, St. Paul, MN 55155 / 651-259-5109


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