Facts of Bald Eagle
Bald Eagles have long rounded wings, large hooked bills, sharp talons, and are the largest birds of prey in the United States. They swoop down on their prey at high speeds, and their diet varies by species and considerably by habitat. In most species, the male is smaller than the female, but otherwise, the sexes are similar in appearance. This family also includes kites and hawks.
The bald eagle (Haliaeetus leucocephalus), is U.S. national symbol. It is a federally designated endangered species. Relatively common in Alaska, populations in the lower 48 States have been seriously diminished, although they are recovering in some areas. Bald eagles are most commonly sighted in coastal areas or near rivers or lakes.
Bald eagles are primarily carrion feeders. Perhaps Bald Eagle sound is not good in listening. Normally they emit a sort of high-pitched giggle or a weak scream showing the classics symbol of adventure. Habitually, Bald Eagle is a very romantic bird of prey, tend to pair for lifetime. They like to share parenting responsibilities with the female. You can listen Bald Eagle sound here
Females are significantly larger than males, but otherwise, the sexes look alike. Body size increases with latitude and is the sole basis by which the northern and southern subspecies are divided. Length from bill tip to tail tip averages 81 cm in the more northerly populations. There may be the reason that female needs extra food reserves to produce her eggs. This is scariest eagle is pretty much always the lady.
Bald Eagle Habitat
Bald eagles generally are restricted to coastal areas, lakes, and rivers. However, in winter areas it is not associated with water. Preferred breeding sites include proximity to large bodies of open water and large nest trees with sturdy branches (often conifers) and areas of old-growth timber with an open and discontinuous canopy.
In a study shows, more than 200 nests, found 55 % within 46 m of shoreline and 92 percent within 183 m of shore. During migration and in winter, conifers often are used for communal roosting both during the day and at night, perhaps to minimize heat loss. Mature trees with large open crowns and stout, horizontal perching limbs are preferred for roosting in general. Bald eagles reach maximum densities in areas of minimal human activity and are almost never found in areas of heavy human use.
Bald Eagle primarily carrion feeders eat dead or dying fish when available but also will catch live fish swimming near the surface or fish in shallow waters. In general, bald eagles can be described as opportunistic feeders, taking advantage of whatever food source is most plentiful. Also, it is easy to scavenge or to capture, including birds and mammals. In many areas, particularly in winter, waterfowl, killed or injured by hunters, and shore birds are an important food source.
Usually, eagles forage in an upland area in the winter season. when surface waters are frozen over, consuming carrion including rabbits, squirrels, and dead domestic livestock such as pigs and chickens. The Bald eagles is also famous in to steal food from other members of their own species as well as from hawks, osprey, gulls, and mergansers.
This Bald Eagle may occur when there is a shortage of a primary food source, such as fish, and an abundance of other prey such as waterfowl being used by other predatory birds. Some prey is important to a few populations; for example, in the Chesapeake Bay region, turtles are consumed during the breeding season, and at Amchitka Island in Alaska, sea otter pups are found regularly in bald eagle nests.
In the Pacific Northwest during the breeding season, that bald eagles hunted live prey 57 percent of the time, scavenged for 24 percent of their prey, and pirated 19 percent (mostly from gulls or other eagles).
Because bald eagles scavenge dead or dying prey, they are particularly vulnerable to environmental contaminants and pesticides (e.g., from feeding on birds that died from pesticides, consuming lead shot from waterfowl killed or disabled by hunters. Bald eagles also are vulnerable to biomagnification of contaminants in food chains.
At the close of Lake Superior (WI), herring gulls, which were consumed by over 20 percent of nesting bald eagle pairs, were found to be a significant source of DDE and PCB intake by the eagles. The gulls contained higher contaminant levels than the local fish because of their higher trophic level.
Adult eagles molt yearly. In northern populations, molting occurs from late spring to early fall; in southern populations, molting may be initiated earlier. It is likely that the molt is not complete, and that some feathers are retained for 2 years. Young bald eagles generally molt into their adult plumage by their fifth year.
Bald eagles migrate out of areas where lakes are completely frozen over in winter but will remain as far north as the availability of open water and a reliable food supply allow. Areas with ice-free waterways, such as the Columbia River estuary in Washington and Oregon, may support both resident and migratory populations in the winter.
The far northern breeding populations migrate south for the winter and often congregate in areas with abundant food, particularly the Mississippi Valley and the northwestern States. Some populations of eagles that breed in southern latitudes (e.g., Arizona, Florida) show a reverse migration and migrate north in midsummer (following breeding), returning south in early autumn or winter. Bald eagles have been observed to nest successfully at 4 years of age, but most do not breed until at least their fifth year. Breeding pairs remain together if both are alive.
Moreover, Bald Eagle is famous for building a massive nest high in the treetops. Both male and female play their role to construct their home to cement their lifelong bond. The nests normally consist of grass and feathers and they used it year after year spruce it up with a whopping foot or two of new material. The nests on average is 2 to 4 feet deep and 5 to 6 feet wide.
Large stick nests (approximately 1.5 m across and 0.6 m deep) are built near water and most often in a large tree, but sometimes on rocky outcrops or even on the ground on some islands. In the absence of disturbance, the same nest site may be used for many years. In Florida, eggs are laid in late autumn or winter, while over the rest of the eagle’s range, mating and egg-laying occur in spring.
Clutch sizes are larger in the north, and both sexes take responsibility for feeding the young. Young fledge at about 10 to 12 weeks of age; after leaving the nest, they are still dependent on their parents for several weeks and often return to the nest for food. After nesting, large groups will often gather at sites with plentiful food and resources, such as along rivers following a salmon spawn.
Bald Eagle Range
During the breeding season, eagles require large areas near open water, with an adequate supply of nesting trees. Distance from human disturbance is an important factor in nest-site selection, and nests have been reported to fail because of disturbance. During incubation and brooding, eagles show territorial defense of an area around the nest site. Following fledging, there is little need for nest defense, and eagles are opportunistic in their search for abundant sources of prey.
During winter, eagles roost communally in large aggregations and share a foraging home range. The population of 150 eagles that fed on meadow voles in a 250-ha flooded field for a 4-week period. This group also established a communal night roost in the vicinity.
Bald Eagle Population
Because population density depends strongly on the configuration of the surface water bodies used for foraging, few investigators have published explicit density estimates on an area basis; most report breeding densities along a shoreline on a linear basis. During the breeding season, 0.03 to 0.4 pairs have been recorded per km shore.
Eagles migrating south from their summer territories in Canada have aggregated in communal roosts of up to 400 eagles in a 40-ha area. In the winter, communal roost sites may also contain large numbers of eagles. A group of 150 eagles that roosted and foraged together in the Klamath Basin, and communal night roosts of up to 300 eagles in Oregon in late winter.
Not all adults in an area are part of the breeding population. Some pairs may establish territories and not breed, while others may not even pair. The percentage of adults breeding and the breeding success of those that do vary with local food abundance, weather, and habitat conditions.
The bioaccumulation of organochlorine pollutants reduced the reproductive success of bald eagles. Now, in many areas, these raptors are reproducing at rates like those prior to the widespread use of these pesticides. Eagles lay one clutch per year, although replacement clutches may be laid upon loss of the initial one. Very little is known about mortality rates of bald eagles.
The population models that adult survival is more important than the reproductive rate to the continued success of bald eagle populations. In captivity, bald eagles have lived for up to 50 years, and one wild eagle, banded and recaptured in Alaska, was estimated to be almost 22 years old.
Upon loss of an initial clutch, bald eagles may lay replacement clutches if enough time remains. Moreover, the average life of bald is around 20 years, however, the oldest confirmed life span is 38 years of age.
The golden eagle (Aquila chrysaetos) is similar in size (81 cm) to the bald eagle. Its range encompasses all but the southeastern United States. Small mammals, snakes, birds, and carrion are primary prey items, and golden eagles prefer mountainous or hilly terrain.
Read More – The Snapping Turtles (Chelydra serpentina)
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Originally posted 2019-09-23 22:01:29.