Editing Bald eagle (section)

==Reproduction==
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. Bald eagles have high mate fidelity and generally [[mate for life]]. However, if one pair member dies or disappears, the survivor will choose a new mate. A pair that has repeatedly failed in breeding attempts may split and look for new mates.<ref>Jenkins, J. M., & Jackman, R. E. (1993). Mate and nest site fidelity in a resident population of Bald Eagles. Condor, 1053-1056.</ref> Bald eagle courtship involves elaborate, spectacular calls and flight displays by the males. The flight includes swoops, chases, and cartwheels, in which they fly high, lock talons, and free-fall, separating just before hitting the ground.<ref name="Stalmaster"/><ref name=r7/><ref>{{cite news |last1=Scharper |first1=Julie |title=Bald eagles fight, tangle and fall out of the sky |url=https://www.baltimoresun.com/features/bs-ae-tangled-bald-eagles-20150127-story.html |access-date=February 14, 2021 |newspaper=Baltimore Sun |date=January 29, 2015}}</ref> Usually, a territory defended by a mature pair will be {{convert|1|to|2|km|mi|abbr=on}} of waterside habitat.<ref name="Travsky"/>

[[File:Dan Pancamo Baytown Bald Eagles Fall 2010-1.jpg|left|thumb|Mating]]
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 from late June to early July.<ref name="Travsky"/> 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 {{convert|4|m|ft|sp=us|abbr = on}} deep, {{convert|2.5|m|ft|sp=us|abbr = on}} across and weigh {{convert|1|t|ST|lk=on|sp=us}}.<ref name="hbw" /> One nest in Florida was found to be {{convert|6.1|m|ft|sp=us|abbr=on}} deep, {{convert|2.9|m|ft|sp=us}} across, and to weigh {{convert|3|ST|t|1|sp=us|abbr=off}}.<ref>{{cite web |author=Erickson, L. |year=2007 |publisher=Journey North |url=http://www.learner.org/jnorth/tm/eagle/NestAbout1.html |title=Bald Eagle, About Bald Eagle Nests |access-date=August 27, 2007 |archive-url=https://web.archive.org/web/20120830211627/http://www.learner.org/jnorth/tm/eagle/NestAbout1.html |archive-date=August 30, 2012 |url-status=dead}}</ref> This nest is on record as the largest tree nest ever recorded for any animal.<ref>{{cite web |url=http://www.trails.com/arts/amazing-bird-records.aspx |title=Amazing Bird Records |website=Trails.com |date=July 27, 2010 |access-date=August 22, 2012}}</ref> Usually nests are used for under five years, 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.<ref name="FPL"/> The nest is built 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.<ref name="Sherrod"/>

[[File:Haliaeetus leucocephalus MWNH 0839.JPG|thumb|Egg, Collection at [[Museum Wiesbaden]] in Germany]]
In [[Sonora]], Mexico, eagles have been observed nesting on top of [[Pachycereus pecten-aboriginum|hecho catcuses]] (''Pachycereus pectin-aboriginum'').<ref name=j9/> 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]].<ref name="Travsky"/> The eggs average about {{convert|73|mm|in|sp=us|abbr = on}} long, ranging from {{convert|58|to|85|mm|in|abbr=on}}, and have a breadth of {{convert|54|mm|in|sp=us|abbr = on}}, ranging from {{convert|47|to|63|mm|in|abbr=on}}.<ref name="Terres"/><ref name="Stalmaster"/> Eggs in Alaska averaged {{convert|130|g|oz|abbr=on}} in mass, while in [[Saskatchewan]] they averaged {{convert|114.4|g|oz|abbr=on}}.<ref name="Hensel, R. J 1964"/><ref name="Bortolotti"/> As with their ultimate body size, egg size tends to increase with distance from the equator.<ref name="Stalmaster"/> 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 in animals|polygyny]].<ref name=bent/> Eagles in captivity have been capable of producing up to seven eggs.<ref name=j10/> It is rare for all three chicks to successfully reach the fledgling stage. The oldest chick often bears the advantage of a larger size and louder voice, which tends to draw the parents' attention towards it.<ref name="Travsky"/> 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.<ref name="Travsky"/> However, nearly half of the known bald eagles produce two fledglings (more rarely three), unlike in some other "eagle" species such as some in the genus ''Aquila'', in which a second fledgling is typically observed in less than 20% of nests, despite two eggs typically being laid.<ref name="Brown"/> 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).<ref name="Travsky"/>

[[File:Back to the Six Mile Lake eagles (Haliaeetus leucocephalus)."feed me mom". (19159890706).jpg|thumb|left|Adult and chick]]
[[File:Bald Eagle Chick, NPSPhoto, Lori Oberhofner (9101506540).jpg|thumb|Chick at [[Everglades National Park]]]]
A young eaglet can gain up to {{convert|170|g|oz|abbr=on}} a day, the fastest growth rate of any North American bird.<ref name="FPL"/> 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 in the air.<ref name="FPL"/> The young fledge at anywhere from 8 to 14 weeks of age, though will remain close to the nest and be 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.<ref name="Bortolotti"/> For the next four years, immature eagles wander widely in search of food until they attain adult plumage and are eligible to reproduce.<ref name="Drexel"/>

Male eagles have been observed killing and cannibalizing their chicks.<ref>{{cite journal |last1=Markham |first1=A. C. |last2=Watts |first2=B. D. |title=Documentation of Infanticide and Cannibalism in Bald Eagles |journal=Journal of Raptor Research |date=2007 |volume=41 |issue=1 |pages=41–44 |doi=10.3356/0892-1016(2007)41[41:DOIACI]2.0.CO;2}}</ref> In 2024 at the National Conservation Training Center in West Virginia, the NCTC's Eagle Cam recorded two bald eagle chicks being attacked and devoured by their father as soon as the mother departed from the nest. The NCTC noted in its statement on the incident that such behavior "has been observed in other nests and is not uncommon in birds of prey."<ref>{{cite news |last1=Kirk |first1=Sam |title=Second chick at NCTC eagle nest in West Virginia killed by father |url=https://fox59.com/news/national-world/second-chick-at-nctc-eagle-nest-in-west-virginia-killed-by-father |agency=Fox 59 |date=April 14, 2024}}</ref>

On rare occasions, bald eagles have been recorded to adopt other raptor fledglings into their nests, as seen in 2017 by a pair of eagles in Shoal Harbor Migratory Bird Sanctuary near Sidney, British Columbia. The pair of eagles in question are believed to have carried a juvenile [[red-tailed hawk]] back to their nest, presumably as prey, whereupon the chick was accepted into the family by both the parents and the eagles' three nestlings.<ref>{{Cite news |url=https://www.bbc.com/news/world-us-canada-40224776 |title=Bald eagle adopts 'mortal enemy' baby hawk |date=June 9, 2017 |access-date=April 4, 2018 |newspaper=BBC News}}</ref> The hawk, nicknamed "Spunky" by biologists monitoring the nest, fledged successfully.<ref>{{cite web |url=https://www.nationalgeographic.com/animals/article/red-tailed-hawk-adopted-by-bald-eagles-video-spd |archive-url=https://web.archive.org/web/20210224094815/https://www.nationalgeographic.com/animals/article/red-tailed-hawk-adopted-by-bald-eagles-video-spd |url-status=dead |archive-date=February 24, 2021 |title=Why This Young Hawk Thinks It's an Eagle |date=July 25, 2017 |website=nationalgeographic.com |access-date=April 4, 2018}}</ref>