<P> Bald eagles are sexually mature at four or five years of age . When they are old enough to breed, they often return to the area where they were born . It is thought that bald eagles mate for life . However, if one member of a pair dies or disappears, the survivor will choose a new mate . A pair which has repeatedly failed in breeding attempts may split and look for new mates . Bald eagle courtship involves elaborate, spectacular calls and flight displays . The flight includes swoops, chases, and cartwheels, in which they fly high, lock talons, and free fall, separating just before hitting the ground . Usually, a territory defended by a mature pair will be 1 to 2 km (0.62 to 1.24 mi) of waterside habitat . </P> <P> Compared to most other raptors which mostly nest in April or May, bald eagles are early breeders: nest building or reinforcing is often by mid-February, egg laying is often late February (sometimes during deep snow in the North), and incubation is usually mid-March and early May . Eggs hatch from mid April to early May, and the young fledge late June to early July . The nest is the largest of any bird in North America; it is used repeatedly over many years and with new material added each year may eventually be as large as 4 m (13 ft) deep, 2.5 m (8.2 ft) across and weigh 1 metric ton (1.1 short tons); one nest in Florida was found to be 6.1 m (20 ft) deep, 2.9 meters (9.5 ft) across, and to weigh 3 short tons (2.7 metric tons). This nest is on record as the largest tree nest ever recorded for any animal . Usually nests are used for under five years or so, as they either collapse in storms or break the branches supporting them by their sheer weight . However, one nest in the Midwest was occupied continuously for at least 34 years . The nest is built out of branches, usually in large trees found near water . When breeding where there are no trees, the bald eagle will nest on the ground, as has been recorded largely in areas largely isolated from terrestrial predators, such as Amchitka Island in Alaska . In Sonora, Mexico, eagles have been observed nesting on top of Hecho catcuses (Pachycereus pectinaboriginum). Nests located on cliffs and rock pinnacles have been reported historically in California, Kansas, Nevada, New Mexico and Utah, but currently are only verified to occur only in Alaska and Arizona . The eggs average about 73 mm (2.9 in) long, ranging from 58 to 85 mm (2.3 to 3.3 in), and have a breadth of 54 mm (2.1 in), ranging from 47 to 63 mm (1.9 to 2.5 in). Eggs in Alaska averaged 130 g (4.6 oz) in mass, while in Saskatchewan they averaged 114.4 g (4.04 oz). As with their ultimate body size, egg size tends to increase further away from the Equator . Eagles produce between one and three eggs per year, two being typical . Rarely, four eggs have been found in nests but these may be exceptional cases of polygyny . Eagles in captivity have been capable of producing up to seven eggs . it is rare for all three chicks to successfully reach the fledging stage . The oldest chick often bears the advantage of larger size and louder voice, which tends to draw the parents attention towards it . Occasionally, as is recorded in many large raptorial birds, the oldest sibling sometimes attacks and kills its younger sibling (s), especially early in the nesting period when their sizes are most different . However, nearly half of known bald eagle produce two fledgings (more rarely three), unlike in some other "eagle" species such as some in the Aquila genus, in which a second fledging is typically observed in less than 20% of nests, despite two eggs typically being laid . Both the male and female take turns incubating the eggs, but the female does most of the sitting . The parent not incubating will hunt for food or look for nesting material during this stage . For the first two to three weeks of the nestling period, at least one adult is at the nest almost 100% of the time . After five to six weeks, the attendance of parents usually drops off considerably (with the parents often perching in trees nearby). A young eaglet can gain up to 170 g (6.0 oz) a day, the fastest growth rate of any North American bird . The young eaglets pick up and manipulate sticks, play tug of war with each other, practice holding things in their talons, and stretch and flap their wings . By eight weeks, the eaglets are strong enough to flap their wings, lift their feet off the nest platform, and rise up in the air . The young fledge at anywhere from 8 to 14 weeks of age, though will remain close to the nest and attended to by their parents for a further 6 weeks . Juvenile eagles first start dispersing away from their parents about 8 weeks after they fledge . Variability in departure date related to effects of sex and hatching order on growth and development . For the next four years, immature eagles wander widely in search of food until they attain adult plumage and are eligible to reproduce . Additionally, as shown by a pair of eagles in Shoal Harbor Migratory Bird Sanctuary located near Sydney, British Columbia on June 9, 2017, bald eagles have been recently recorded to occasionally adopt other raptor fledglings into their nests . The pair of eagles in question were recorded carrying a juvenile red - tailed hawk back to their nest, whereupon the chick was accepted into the family by both the parents and the eagles' three fledgelings . Whether or not the chick survived remained to be seen at the time, as bald eagles are known for committing fratricide amongst their siblings . However, the aggression of the red - tailed hawk may ensure its survival, as the hawks are well known for their ability to successfully defend against an eagle attack . Six weeks after however, it was discovered that the hawk, nicknamed "Spunky" by biologists monitoring the nest, had grown to fledgeling size and was learning how to hunt, indicating that it successfully survived . </P> <P> The average lifespan of bald eagles in the wild is around 20 years, with the oldest confirmed one having been 38 years of age . In captivity, they often live somewhat longer . In one instance, a captive individual in New York lived for nearly 50 years . As with size, the average lifespan of an eagle population appears to be influenced by its location and access to prey . As they are no longer heavily persecuted, adult mortality is quite low . In one study of Florida eagles, adult bald eagles reportedly had 100% annual survival rate . In Prince William Sound in Alaska, adults had an annual survival rate of 88% even after the Exxon Valdez oil spill adversely affected eagles in the area . Of 1,428 individuals from across the range necropsied by National Wildlife Health Center from 1963 to 1984, 329 (23%) eagles died from trauma, primarily impact with wires and vehicles; 309 (22%) died from gunshot; 158 (11%) died from poisoning; 130 (9%) died from electrocution; 68 (5%) died from trapping; 110 (8%) from emaciation; and 31 (2%) from disease; cause of death was undetermined in 293 (20%) of cases . In this study, 68% of mortality was human - caused . Today eagle - shooting is believed to be considerably reduced due to the species protected status . In one case, an adult eagle investigating a peregrine falcon nest for prey items sustained a concussion from a swooping parent peregrine, and ultimately died days later from it . An early natural history video depicting a cougar (Puma concolor) ambushing and killing an immature bald eagle feeding at a rabbit carcass is viewable online although this film may have been staged . </P> <P> Most non-human - related mortality involves nestlings or eggs . Around 50% of eagles survive their first year . However, in the Chesapeake Bay area, 100% of 39 radio - tagged nestlings survived to their first year . Occasionally, nestling or egg fatalities are due to nest collapses, starvation, sibling aggression or inclement weather . Another significant cause of egg and nestling mortality is predation . These have been verified to be preyed by large gulls, corvids (including ravens, crows and magpies), wolverines (Gulo gulo), hawks, owls, eagles, bobcats (Lynx rufus), American black bears (Ursus americanus) and raccoons . If food access is low, parental attendance at the nest may be lower because both parents may have to forage thus resulting in less protection . Nestlings are usually exempt from predation by terrestrial carnivores that are poor tree - climbers, but Arctic foxes (Vulpes lagopus) occasionally snatched nestlings from ground nests on Amchitka Island in Alaska before they were extirpated from the island . The bald eagle will defend its nest fiercely from all comers and has even repelled attacks from bears, having been recorded knocking a black bear out of a tree when the latter tried to climb a tree holding nestlings . </P>

How many years can a bald eagle live