Bald Eagle

More info for the term: cover

See ECOSYSTEMS, PLANT ASSOCIATIONS, and COVER TYPES.

bald eagle
American eagle

Information on state- and province-level protection status of animals in
the United States and Canada is available at NatureServe, although recent
changes in status may not be included.

More info for the terms: cover, tree

Habitat suitability index models have been developed for wintering bald
eagles in lacustrine and estuarine habitats of the central and northern
states [25]. Bald eagles need old-growth or late-successional forests
for nesting and roosting [20]. Nest snags must be sturdy to support
nests. Tree height or species is not as important as the abundance of
comparatively large trees near feeding areas [11]. Lakes greater than
3.8 square miles (10 sq km) may be optimal for breeding bald eagles,
although longer and narrower bodies of water can support breeding pairs.
Nest trees should have an open form and sturdy branches in the upper
one-third of the tree. Eagles nest in the overstory. Forests used for
nesting should have a canopy cover of less than 60 percent (may be as
low as 20 percent) and be near water. In treeless areas, bald eagles
nest on cliffs or on the ground [25].

Roosting sites need not be as near to water as nesting sites. It is
more important that roosting sites are in dense stands of old growth
that offer protection from weather. Eagles usually arrive at roost
sites after dark and depart roost sites before dawn. It is therefore is
difficult to determine important roost sites through daytime observation
[13].

Average home ranges for eight pairs of bald eagles in Oregon were 1,650
acres (660 ha), with an average distance between nest territories of 2
miles (3.2 km), and an average of 0.3 miles (0.5 km) of shoreline per
pair [16]. In Arizona, the estimate was 24.6 square miles (64 sq km) of
home range, with 9.4 to 11.2 miles (15-18 km) of shoreline for each pair.

The bald eagle breeds from central Alaska across Canada to Labrador and
Newfoundland and south to southern mainland Alaska and the Aleutian
Islands [29]. It also breeds in Baja California, central Arizona,
southwestern and central New Mexico, and along the Gulf Coast from Texas
to Florida [1,29]. The bald eagle occurs only locally throughout much
of the Great Basin and Great Plains [1]. Bald eagles winter in most of
their breeding range, from southern Alaska and Canada southward [1,29].
Resident populations are found along the Atlantic, Pacific, and Gulf
coasts [16].

Bald eagles eat fish, reptiles, birds, mammals, invertebrates and
carrion, including that of livestock. Some food species of eagles
include bullhead fish (Ictalurus spp.), alewife (Alosa pseudoharengus),
chain pickerel (Esox niger), sucker (Catostomus spp.), salmon
(Oncorhyncus spp.), white perch (Morone americana), smallmouth bass
(Micropterus dolomieui), eel (Anguilla rostrata), sea otter (Enhydra
lutris), grebe (Podilymbus podiceps), Canada goose (Branta canadensis),
American coot (Fulica americana), mallard (Anas platyrhynchos), pintail
(A. acuta), hare (Lepus spp.), and prairie dog (Cynomys spp.) [17,18,21,25].

More info for the terms: forest, fuel, fuel loading, snag, stand-replacing fire

Because forest structure (density and height class) determines avian
community composition, changes in forest structure lead to changes in
avian communities [30,31]. A stand-replacing fire will, therefore,
likely change bald eagle use of a forest. Fires that destroy old-growth
forest can reduce eagle populations [28]. If low-intensity,
litter-reducing fires are not allowed to burn in old-growth forests,
stand-replacing, high-intensity crown fires can result [6].

Fires create snags, which are important perching and nesting sites for
bald eagles. Snags can possibly increase potential for lightning-caused
fire when standing, and when fallen, they increase fuel loading [33].
These increased potentials may be hazardous in areas where fire control
for maintaining bald eagle populations is necessary. There have been no
studies to determine if the hazards of snags outweigh their benefits to
eagles. Snag attrition rates have been listed for lodgepole pine
forests following fire [33]. Old-growth eastern white pine (Pinus
strobus) forests in Ontario continually recruit snags in the absence of
fire because of their uneven-aged structure [32]. Catastrophic fires in
mature and old-growth forests can create even-aged conditions which may
stop continuous snag recruitment [32].

More info on this topic.

This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

More info for the term: hardwood

1 Jack pine
5 Balsam fir
12 Black spruce
13 Black spruce - tamarack
15 Red pine
16 Aspen
18 Paper birch
21 Eastern white pine
22 White pine - hemlock
23 Eastern hemlock
30 Red spruce - yellow birch
32 Red spruce
33 Red spruce - balsam fir
34 Red spruce - Fraser fir
35 Paper birch - red spruce - balsam fir
38 Tamarack
40 Post oak - blackjack oak
42 Bur oak
62 Silver maple - American elm
63 Cottonwood
78 Virginia pine - oak
79 Virginia pine
81 Loblolly pine
82 Loblolly pine - hardwood
105 Tropical hardwoods
107 White spruce
201 White spruce
202 White spruce - paper birch
203 Balsam poplar
204 Black spruce
205 Mountain hemlock
206 Engelmann spruce - subalpine fir
207 Red fir
210 Interior Douglas-fir
211 White fir
212 Western larch
213 Grand fir
215 Western white pine
216 Blue spruce
217 Aspen
218 Lodgepole pine
219 Limber pine
220 Rocky Mountain juniper
222 Black cottonwood - willow
223 Sitka spruce
224 Western hemlock
225 Western hemlock - Sitka spruce
226 Coastal true fir - hemlock
227 Western redcedar - western hemlock
228 Western redcedar
229 Pacific Douglas-fir
230 Douglas-fir - western hemlock
234 Douglas-fir - tanoak - Pacific madrone
235 Cottonwood - willow
237 Interior ponderosa pine
238 Western juniper
239 Pinyon - juniper
243 Sierra Nevada mixed conifer
244 Pacific ponderosa pine - Douglas-fir
245 Pacific ponderosa pine
246 California black oak
250 Blue oak - Digger pine
251 White spruce - aspen
252 Paper birch
253 Black spruce - white spruce
254 Black spruce - paper birch
256 California mixed subalpine

More info on this topic.

This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

More info for the term: shrub

FRES10 White-red-jack pine
FRES11 Spruce-fir
FRES13 Loblolly-shortleaf pine
FRES14 Oak-pine
FRES15 Oak-hickory
FRES17 Elm-ash-cottonwood
FRES19 Aspen-birch
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES22 Western white pine
FRES23 Fir-spruce
FRES24 Hemlock-Sitka spruce
FRES25 Larch
FRES26 Lodgepole pine
FRES28 Western hardwoods
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES35 Pinyon-juniper
FRES36 Mountain grasslands
FRES37 Mountain meadows

More info on this topic.

This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the terms: bog, forest, woodland

K001 Spruce - cedar - hemlock forest
K002 Cedar - hemlock - Douglas-fir forest
K003 Silver fir - Douglas-fir forest
K004 Fir - hemlock forest
K005 Mixed conifer forest
K008 Lodgepole pine - subalpine forest
K011 Western ponderosa forest
K012 Douglas-fir forest
K013 Cedar - hemlock - pine forest
K014 Grand fir - Douglas-fir forest
K015 Western spruce - fir forest
K016 Eastern ponderosa forest
K017 Black Hills pine forest
K018 Pine - Douglas-fir forest
K019 Arizona pine forest
K020 Spruce - fir - Douglas-fir forest
K021 Southwestern spruce - fir forest
K022 Great Basin pine forest
K023 Juniper - pinyon woodland
K024 Juniper steppe woodland
K029 California mixed evergreen forest
K030 California oakwoods
K034 Montane chaparral
K037 Mountain-mahogany - oak scrub
K038 Great Basin sagebrush
K092 Everglades
K093 Great Lakes spruce - fir forest
K094 Conifer bog
K095 Great Lakes pine forest
K096 Northeastern spruce - fir forest
K097 Southeastern spruce - fir forest
K098 Northern floodplain forest
K101 Elm - ash forest
K103 Mixed mesophytic forest
K106 Northern hardwoods
K107 Northern hardwoods - fir forest
K108 Northern hardwoods - spruce forest
K113 Southern floodplain forest

Humans pose the greatest threat to bald eagles through habitat
destruction, pesticide use, and poaching [3,8].

In order of increasing ease, bald eagles are flushed from perches,
nests, and foraging areas by human disturbance [14]. They are most
easily disturbed by pedestrian traffic and least disturbed by aircraft.
Establishing buffer zones of 148 to 296 feet (400-800 m) in Oregon and
167 to 592 feet (450-1,600 m) in the Southeast was recommended to
reduce the impact of human disturbance on nesting pairs [14].

Silvicultural treatments for maintaining eagle habitat in ponderosa pine
(Pinus ponderosa) of various age and structure, subclimax mixed conifer,
Douglas-fir (Pseudotsuga menziesii) , and oak (Quercus lobata; Q.
kelloggii) stands in northeastern California are detailed [4].

AL
AK
AZ
AR
CA
CO
CT
DE
FL
GA

ID
IL
IN
IA
KS
KY
LA
ME
MD
MA

MI
MN
MS
MO
MT
NE
NV
NH
NJ
NM

NY
NC
ND
OH
OK
OR
PA
RI
SC
SD

TN
TX
UT
VT
VA
WA
WV
WI
WY
DC


AB
BC
MB
NB
NF
NT
NS
ON
PE
PQ

SK
YK


MEXICO

More info for the term: forest

Bald eagles prefer habitat near seacoasts, rivers, large lakes, and
other large areas of open water [25]. They prefer to nest, perch, and
roost primarily in old-growth and mature stands of conifers or
hardwoods. Eagles usually select the oldest and tallest trees that have
good visibility, an open structure, and are near prey [9,11,16,18,26]. A
study in Maine showed a preference for areas with "superdominant" trees.
It also showed bald eagles avoided lakes surrounded by dense forest or
inhabited by cold-water fishes. They used areas away from human
disturbance and selected nesting sites near lakes with an abundance of
warm-water fishes [21]. Another study showed a preference for nesting
near lakes with a circumference greater than 7-mile (11-km). The
smallest body of water supporting a nesting pair of bald eagles was 20
acres (8 ha) [25].

Eagles choose sites more than 0.75 miles (1.2 km) from low-density human
disturbance and more than 1.2 miles (1.8 km) from medium- to
high-density human disturbance [25]. Wintering bald eagles in New
Mexico and Arizona used a disproportionate amount of snags in the
largest class size (no d.b.h. given) for perching, and usually perched
in the top one-third of these trees. For roosting, eagles preferred
the largest live trees with open structures for visibility [13].

More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands

The currently accepted scientific name for bald eagle is Haliaeetus
leucocephalus (Linnaeus) [1]. Two subspecies, Haliaeetus leucocephalus
ssp. leucocephalus and Haliaeetus leucocephalus ssp. alascanus Townsend,
have been identified [16].

Mate - late September through November in the South; January through
March in the central states; late March to early April in
Alaska; can vary with elevation as well as latitude; usually
mate for life
Maturity - 4 to 5 years
Clutch - two eggs
Incubation - 35 days
Fledge - 10 to 12 weeks
Longevity - up to 36 years in captivity [12,16]

The bald eagle is federally protected under the Bald Eagle Protection
Act of 1962 [34].

More info for the terms: fire regime, litter

Fire can be used to reduce litter build-up, control disease, remove less
vigorous species, and allow more vigorous trees to reach maturity, thus
providing old-growth habitat for bald eagles [15].

FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find FIRE REGIMES".