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[[File:Bald Eagle on Seedskadee NWR (24062616030).jpg|thumb|left|upright|Carrying a caught [[cottontail rabbit]] in [[Seedskadee National Wildlife Refuge]]]]
[[File:Haliaeetus leucocephalus-whale-USFWS.jpg|thumb|right|A bald eagle on a whale carcass]]
[[Mammal]]ian preys are generally less frequently taken than fish or avian prey. However, in some regions, such as landlocked areas of North America, wintering bald eagles may become habitual predators of medium-sized mammals that occur in colonies or local concentrations, such as [[prairie dog]]s (''Cynomys'' sp.) and [[jackrabbit]]s (''Lepus'' sp.).<ref name="Travsky"/><ref name="Jones"/> Bald eagles in [[Seedskadee National Wildlife Refuge]] often hunt in pair to catch
Where available, seal colonies can provide a lot of food. On [[Protection Island (Washington state)|Protection Island]], [[Washington (state)|Washington]], they commonly feed on [[harbor seal]] (''Phoca vitulina'') afterbirths, still-borns and sickly seal pups.<ref name="Hayward"/> Similarly, bald eagles in Alaska readily prey on [[sea otter]] (''Enhydra lutris'') pups.<ref>{{cite journal |last1=Sherrod |first1=S. K. |first2=C. M. |last2=White |first3=F. S. L. |last3=Williamson |year=1976 |title=Biology of the Bald Eagle on Amchitka Island, Alaska |journal=The Living Bird |volume=15 |pages=143–182}}</ref> Small to medium-sized terrestrial mammalian carnivores can be taken infrequently. [[Mustelid]] including [[American marten]]s (''Martes pennanti''),<ref>{{cite journal |first1=Roger A. |last1=Powell |title=''Martes pennanti'' |journal=Mammalian Species |issue=156 |date=8 May 1981 |pages=1–6 |doi=10.2307/3504050|jstor=3504050 |doi-access=free }}</ref>,[[American mink]]s (''Neogale vison''),<ref>{{cite journal| last1=Watson |first1=James W. |doi=10.2307/3536608 |title=Comparative Home Ranges and Food Habits of Bald Eagles Nesting in Four Aquatic Habitats in Western Washington |journal=Northwestern Naturalist |volume=83 |issue=3 |publisher=Society for Northwestern Vertebrate Biology |year=2002 |pages=101–08|jstor=3536608 }}</ref>, and larger [[fisher cat]]s (''Pekania pennanti'') are known to be hunted.<ref>{{cite journal|last1=Erb|first1=John|first2=B.|last2=Sampson|first3=P.|last3=Coy|title=Survival and causes of mortality for fisher and marten in Minnesota|journal=Minn. Dep. Nat. Resour. Summ. Wildl. Res. Findings|year=2010|pages=24–31}}</ref> [[Fox]]es are also taken, including [[Island fox]]es ('' Urocyon littoralis ''),<ref>{{cite journal |first1=Claybourne M. |last1=Moore |first2=Paul W. |last2=Collins |title=''Urocyon littoralis'' |journal=Mammalian Species |issue=489 |date=23 June 1995 |pages=1–7 |doi=10.2307/3504160|jstor=3504160 |s2cid=215746001 |doi-access=free }}</ref> [[Arctic fox]]es (''Vulpes lagopus''),<ref>{{cite journal |first1=Alexandra M. |last1=Audet |first2=C. Brian |last2=Robbins |first3=Serge |last3=Larivière |doi=10.1644/0.713.1 |title=''Alopex lagopus'' |journal=Mammalian Species |issue=713 |date=26 December 2002 |pages=1–10|doi-access=free }}</ref> and [[grey fox]]es (''Urocyon cinereoargenteus'').<ref name = 'Oberholser'>{{cite book |last1=Oberholser |first1=Harry Church |title=The North American eagles and their economic relations |year=1906}}</ref> Although fox farmers claimed that bald eagle heavily prey on young and adult free-range Arctic fox, the predation events are sporadic.<ref name=bent/><ref>Anthony, R. G., Estes, J. A., Ricca, M. A., Miles, A. K., & Forsman, E. D. (2008). Bald eagles and sea otters in the Aleutian archipelago: indirect effects of trophic cascades. Ecology, 89(10), 2725-2735.</ref> In one instance, two bald Eagles fed upon a [[red fox]] (''Vulpes vulpes'') that had tried to cross a frozen [[Delaware Lake]].<ref>{{cite web |url=https://columbusaudubon.org/auto-da-gathering-of-eaglesraft/| title=A Gathering of Eagles| website=Columbus Audubon}}</ref> Other medium-sized carnivorans such as [[striped skunk]]s (''Mephitis mephitis''),<ref>{{cite journal |first1=Julia |last1=Wade-Smith |first2=B. J. |last2=Verts |doi=10.2307/3503883 |title=''Mephitis mephitis'' |journal=Mammalian Species |issue=173 |date=25 May 1982 |pages=1–7|jstor=3503883 |doi-access=free }}</ref> [[American hog-nosed skunk]]s (''Conepatus leuconotus''),<ref>{{Cite journal|journal=Mammalian Species|doi=10.1644/827.1|title=Conepatus leuconotus (Carnivora: Mephitidae) |year=2009 |last1=Dragoo |first1=Jerry W. |last2=Sheffield |first2=Steven R. |volume=827 |pages=1–8 |s2cid=86591926 |doi-access=free }}</ref> and [[common raccoon]]s (''Procyon lotor'')<ref name = 'Oberholser'/> are taken, as well as [[domestic cat]]s (''Felis catus'') and [[dog]]s (''canis familiaris'').<ref>{{Cite web|title=Two young eagles preying on cats in Campbell River|url=https://www.timescolonist.com/local-news/two-young-eagles-preying-on-cats-in-campbell-river-4608302
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===Reptiles and other prey===
Supplemental prey is readily taken given the opportunity. In some areas, reptiles may become regular prey, especially in warm areas such as Florida where reptile diversity is high. Turtles are perhaps the most regularly hunted type of reptile.<ref name="Travsky"/> In coastal [[New Jersey]], 14 of 20 studied eagle nests included remains of turtles. The main species found were [[Sternotherus odoratus|common musk turtles]] (''Sternotherus odoratus''), [[diamondback terrapin]] (''Malaclemys terrapin'') and juvenile [[common snapping turtle]]s (''Chelydra serpentina''). In these New Jersey nests, mainly subadult and small adults were taken, ranging in carapace length from {{convert|9.2|to|17.1|cm|in|abbr=on}}.<ref name="Wetlands"/> Similarly, many turtles were recorded in the diet in the [[Chesapeake Bay]].<ref>{{cite journal |last1=Clark |first1=W. S. |year=1982 |title=Turtles as a food source of nesting bald eagles in the Chesapeake Bay region |journal=Journal of Field Ornithology |volume=53 |issue=1 |pages=49–51}}</ref> In [[Texas]], [[Apalone|softshell turtle]]s are the most frequently taken prey,<ref>{{cite journal |last1=Mabie |first1=David W. |first2=M. Todd |last2=Merendino |first3=David H. |last3=Reid |title=Prey of nesting bald eagles in Texas |journal=Journal of Raptor Research |volume=29 |issue=1 |year=1995 |pages=10–14}}</ref> and a large number of [[Barbour's map turtle]]s are taken in [[Torreya State Park]].<ref>{{cite journal |last1=Means |first1=D. Bruce |first2=A. N. N. E. |last2=Harvey |title=Barbour's map turtle in the diet of nesting bald eagles |journal=Florida Field Naturalist |volume=27 |issue=1 |year=1999 |pages=14–16}}</ref> Other reptilian and amphibian prey includes [[southern alligator lizard]]s (''Elgaria multicarinata''),<ref name = 'Erlandson.'/> snakes such as [[garter snake]]s and [[rattlesnake]]s,<ref name="FPL"/><ref>{{Cite journal |last=Olson |first=Storrs L. |date=2006-10-01 |title=Bald Eagle, Haliaeetus leucocephalus, Preying on Maritime Garter Snake, Thamnophis sirtalis pallidulus, on Cape Breton Island, Nova Scotia |url=http://www.canadianfieldnaturalist.ca/index.php/cfn/article/view/359 |journal=The Canadian Field-Naturalist |volume=120 |issue=4 |pages=477 |doi=10.22621/cfn.v120i4.359 |issn=0008-3550|doi-access=free }}</ref><ref>{{cite journal |last1=Grubb |first1=Teryl G. |title=Food habits of bald eagles breeding in the Arizona desert |journal=The Wilson Bulletin |year=1995 |pages=258–274}}</ref><ref name = 'Beans'/> and [[Greater siren]] (''Siren lacertina'').<ref name="McEwan, Linda C. 1980"/>
Invertebrates are occasionally taken. In [[Alaska]], eagles feed on [[sea urchin]]s (''Strongylocentrotus'' sp.), chitons, mussels, and crabs.<ref>{{cite journal |first1=J.M. |last1=Erlandson |first2=M.L. |last2=Moss |title=Shellfish feeders, carrion eaters, and aquatic adaptations |journal=American Antiquity |volume=66 |year=2001 |pages=413–432|doi=10.2307/2694242 |jstor=2694242 |s2cid=83743872 }}</ref> Other various mollusks such as [[land snail]]s, [[abalones]], [[bivalves]], [[Littorinidae|periwinkles]], [[blue mussels]], [[squid]]s, and [[starfish]]es are taken as well.<ref name = 'Erlandson.'/>
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==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.
[[File:Dan Pancamo Baytown Bald Eagles Fall 2010-1.jpg|left|thumb|Mating]]
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[[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}}</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=14 April 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>
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==Longevity and mortality==
[[File:Fledging Bald Eagle.jpg|thumb|Newly fledged juvenile]]
The average lifespan of bald eagles in the wild is around 20 years, with the oldest confirmed one having been 38 years of age.<ref>{{cite web|url=http://www.washingtontimes.com/news/2015/jun/14/bald-eagle-believed-oldest-banded-of-its-species-f/ |title=Bald eagle believed oldest banded of its species found dead |publisher=Washington Times (Associated Press) |date=June 14, 2015}}</ref> In captivity, they often live somewhat longer. In one instance, a captive individual in New York lived for nearly 50 years.{{cn|date=July 2024}} As with size, the average lifespan of an eagle population appears to be influenced by its location and access to prey.<ref name=sop>{{cite web|url=http://www.bsc-eoc.org/regional/oneaglefacts.html |title=Bald Eagle Fact Sheet |publisher=Southern Ontario Bald Eagle Monitoring Project |access-date=June 30, 2008 |url-status=dead |archive-url=https://web.archive.org/web/20080511232457/http://www.bsc-eoc.org/regional/oneaglefacts.html |archive-date=May 11, 2008}}</ref> 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.<ref name= Watson/> 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.<ref name=j16/> 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.<ref name="Buehler"/> In this study, 68% of mortality was human-caused.<ref name="Buehler" /> Today, eagle-shooting is believed to be considerably reduced due to the species' protected status.<ref name=b6/> A [[U.S. Fish and Wildlife Service]] study of 1,490 bald eagle deaths from 1986 through 2017 in [[Michigan]] found that 532 (36%) died due to being struck by cars while scavanging [[roadkill]] and 176 (12%) died due to [[lead poisoning]] from ingesting fragments of lead ammo and fishing gear present in [[carrion]], with the proportion of both causes of death increasing significantly towards the end of the study period.<ref>{{cite news |last1=Matheny |first1=Keith |title=What kills bald eagles in Michigan? Most comprehensive study ever has the answers |url=https://www.freep.com/story/news/local/michigan/2020/08/07/leading-killer-bald-eagles-michigan-isnt-what-you-think/5572129002/ |access-date=23 July 2024 |work=Detroit Free Press |date=7 August 2020}}</ref><ref name=simon>{{Cite journal |
Most non-human-related mortality involves nestlings or eggs. Around 50% of eagles survive their first year.<ref name="Drexel"/> However, in the Chesapeake Bay area, 100% of 39 radio-tagged nestlings survived to their first year.<ref name=j24/> Nestling or egg fatalities may be due to nest collapses, starvation, sibling aggression or inclement weather. Another significant cause of egg and nestling mortality is predation. Nest predators include large [[gull]]s, [[corvid]]s (including ravens, [[Corvus (genus)|crows]] and [[magpie]]s), [[wolverine]]s (''Gulo gulo''), [[Fisher (animal)|fishers]] (''Pekania pennanti''), [[red-tailed hawk]]s, owls, other [[eagle]]s, bobcats, [[American black bear]]s (''Ursus americanus'') and raccoons.<ref name="Hensel, R. J 1964"/><ref name=j17/><ref name=j18a/><ref name=j19/><ref name=j20/><ref name=j21/><ref name=j22/><ref>{{cite journal |last1=Lovallo |first1=M. J. |year=2008 |title=Status and management of fisher (''Martes pennanti'') in Pennsylvania |journal=Management Plan Developed by Bureau of Wildlife Management |publisher=Pennsylvania Game Commission |location=Harrisburg, USA}}</ref> 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.<ref name="Brown"/> Nestlings are usually exempt from predation by terrestrial carnivores that are poor tree-climbers, but [[Arctic fox]]es (''Vulpes lagopus'') occasionally snatched nestlings from ground nests on Amchitka Island in Alaska before they were extirpated from the island.<ref name="Sherrod"/> 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.<ref name="Redoubt">{{YouTube|OTr0qkC5sZw|Bald Eagle attacks Black bear again at Redoubt Bay}}</ref>
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===Population decline and recovery===
[[File:Trash eagle.jpg|thumb|Inside a waste collection and transfer facility, in [[Homer, Alaska]], United States]]
Once a common sight in much of the continent, the bald eagle was severely affected in the mid-20th century by a variety of factors, among them the thinning of egg shells attributed to use of the pesticide [[DDT]].<ref name=b5/> Bald eagles, like many birds of prey, were especially affected by DDT due to [[biomagnification]]. DDT itself was not lethal to the adult bird, but it interfered with their [[calcium]] metabolism, making them either sterile or unable to lay healthy eggs; many of their eggs were too brittle to withstand the weight of a brooding adult, making it nearly impossible for them to hatch.<ref name="Bull87"/> It is estimated that in the early 18th century the bald eagle population was 300,000–500,000,<ref name=r16/> but by the 1950s there were only 412 nesting pairs in the 48 [[Contiguous United States|contiguous states]] of the US.<ref>{{cite web|url=https://nationalzoo.si.edu/support/adopt/adopt-bald-eagle|title=Adopt a Bald Eagle|publisher=Smithsonian's National Zoo & Conservation Biology Institute|access-date=August 4, 2018|date=May 26, 2016|archive-date=February 9, 2021|archive-url=https://web.archive.org/web/20210209052703/https://nationalzoo.si.edu/support/adopt/adopt-bald-eagle|url-status=dead}}</ref><ref>{{cite web|url=http://www.dnr.sc.gov/wildlife/baldeagle/pastsurveys.html|title=South Carolina's Bald Eagles – Past Surveys|publisher=South Carolina Department of Natural Resources|date=2015|access-date=August 4, 2018}}</ref>
Other factors in bald eagle population reductions were a widespread loss of suitable habitat, as well as both legal and illegal shooting. In 1930 a New York City ornithologist wrote that in the territory of Alaska in the previous 12 years approximately 70,000 bald eagles had been shot. Many of the hunters killed the bald eagles under the long-held beliefs that bald eagles grabbed young lambs and even children with their talons, yet the birds were innocent of most of these alleged acts of predation (lamb predation is rare, human predation is thought to be non-existent).<ref>{{cite magazine |url=https://books.google.com/books?id=HCoDAAAAMBAJ&pg=PA62 |title=American Bald Eagle Is Near Extinction |magazine=Popular Science Monthly |date=March 1930 |page=62}}</ref> Illegal shooting was described as "the leading cause of direct mortality in both adult and immature bald eagles" by the U.S. Fish and Wildlife Service in 1978.<ref>{{cite journal |title=Bald Eagle's Status Listed for 48 States |journal=Endangered Species Technical Bulletin |date=March 1978 |volume=III |issue=3 |page=9}}</ref> Leading causes of death in bald eagles include lead pollution, poisoning, collision with motor vehicles, and power-line electrocution.<ref>{{cite journal |url=https://www.researchgate.net/publication/264861144 |title=Causes of Mortality in Eagles Submitted to The National Wildlife Health Center 1975–2013 |last1=Russell |first1=Robin E. |last2=Franson |first2=J. Christian |date=December 2014 |journal=Wildlife Society Bulletin |volume=38 |number=4 |pages=697–704 |doi=10.1002/wsb.469|bibcode=2014WSBu...38..697R }}</ref> A study published in 2022 in the journal Science found that more than half of adult eagles across 38 US states suffered from lead poisoning.<ref name="lead1"/> The primary cause is when eagles scavenge carcasses of animals shot by hunters.<ref name="lead1"/> These are often tainted with lead shotgun pellets, rifle rounds, or fishing tackle.<ref name="lead1">{{cite web |title=Most U.S. eagles suffer from lead poisoning, study suggests| first= Douglas| last= Main |website=National Geographic |url=https://www.nationalgeographic.com/animals/article/bald-eagles-golden-eagles-lead-poisoning-ammunition |date= February 17, 2022 |archive-url=https://web.archive.org/web/20230223131707/https://www.nationalgeographic.com/animals/article/bald-eagles-golden-eagles-lead-poisoning-ammunition |archive-date=February 23, 2023}}</ref><ref name="simon" />
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<ref name="Hensel, R. J 1964">{{cite journal|author=Hensel, R. J. |author2= Troyer, W. A. |year=1964|title=Nesting studies of the Bald Eagle in Alaska|journal= Condor |volume=66|pages=282–86|url=http://sora.unm.edu/node/105929|doi=10.2307/1365287|issue=4|jstor=1365287}}</ref>
<ref name="ICWDM">{{cite web |url=http://icwdm.org/handbook/birds/eagles.asp |title=Bald and Golden Eagles damage management and predation control |author=O'Gara, B. |publisher=Cooperative Extension Division Institute of Agriculture and Natural Resources University of Nebraska |access-date=January 3, 2013 |date=August 3, 1994 |archive-url=https://web.archive.org/web/20120615065921/http://icwdm.org/handbook/birds/eagles.asp |archive-date=June 15, 2012 |url-status=dead}}</ref>
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