Mount Chiginagak is a stratovolcano on the Alaska Peninsula, located about 15 km northwest of Chiginagak Bay.
124-607: An unglaciated lava flow and an overlying pyroclastic-flow deposit extending east from the summit are the most recent products of Chiginagak. They most likely originated from a lava dome at 1687m on the SE flank, 1 km from the summit of the volcano. Brief ash eruptions were reported in July 1971 and August 1998. Fumarolic activity occurs at 1600m elevation on the NE flank of the volcano, and two areas of hot-spring travertine deposition are located at
248-655: A gull 's call. The calls of young birds tend to be more harsh and shrill than those of adults. The bald eagle's natural range covers most of North America, including most of Canada, all of the continental United States , and northern Mexico. It is the only sea eagle endemic to North America. Occupying varied habitats from the bayous of Louisiana to the Sonoran Desert and the eastern deciduous forests of Quebec and New England , northern birds are migratory , while southern birds are resident, remaining on their breeding territory all year. At minimum population, in
372-539: A species pair with the white-tailed eagle ( Haliaeetus albicilla ), which occupies the same niche as the bald eagle in the Palearctic . Its range includes most of Canada and Alaska , all of the contiguous United States , and northern Mexico . It is found near large bodies of open water with an abundant food supply and old-growth trees for nesting. The bald eagle is an opportunistic feeder which subsists mainly on fish , which it swoops down upon and snatches from
496-877: A bald eagle flies close by, waterbirds will often fly away en masse, though they may seemingly ignore a perched eagle in other cases. when the birds fly away from a colony, this exposes their unprotected eggs and nestlings to scavengers such as gulls . While they usually target small to medium-sized seabirds, larger seabirds such as great black-backed gulls ( Larus marinus ) and northern gannets ( Morus bassanus ) and brown pelicans ( Pelecanus occidentalis ) of all ages can successfully be taken by bald eagles. Similarly, large waterbirds are occasionally killed. Geese such as wintering emperor geese ( Chen canagica ) and snow geese ( C. caerulescens ), which gather in large groups, sometimes becoming regular prey. Smaller Ross's geese ( Anser rossii ) are also taken, as well as large-sized Canada geese ( Branta canadensis ). Predation on
620-546: A bald eagle was observed carrying 6.8 kg (15 lb) mule deer ( Odocoileus hemionus ) fawn. Additionally, Virginia opossums ( Didelphis virginiana ) can be preyed upon. Still, predation events are rare due to their nocturnal habits. Together with the golden eagle, bald eagles are occasionally accused of preying on livestock, especially sheep ( Ovis aries ). There are a handful of proven cases of lamb predation, some specimens weighing up to 11 kg (24 lb), by bald eagles. Still, they are much less likely to attack
744-466: A body length of 70–102 cm (28–40 in). Typical wingspan is between 1.8 and 2.3 m (5 ft 11 in and 7 ft 7 in) and mass is normally between 3 and 6.3 kg (6.6 and 13.9 lb). Females are about 25% larger than males, averaging as much as 5.6 kg (12 lb), and against the males' average weight of 4.1 kg (9.0 lb). The size of the bird varies by location and generally corresponds with Bergmann's rule :
868-432: A cliff or other terrain. Migration generally takes place during the daytime, usually between the local hours of 8:00 a.m. and 6:00 p.m., when thermals are produced by the sun. The bald eagle is an opportunistic carnivore with the capacity to consume a great variety of prey. Fish often comprise most of the eagle's diet throughout their range. In 20 food habit studies across the species' range, fish comprised 56% of
992-414: A couple of weeks. Once the salmon die in the river, they are either scavenged by other animals, or they decompose and release inorganic nutrients to the plankton in the river and the riparian vegetation in the floodplain . The Pacific salmon are a classic example of a semelparous animal, which reproduce only once in their lifetime. Semelparity is sometimes called "big bang" reproduction, since
1116-401: A gravel bed in the upper reaches of a stream or river. These are the salmon spawning grounds where salmon eggs are deposited, for safety, in the gravel. The salmon spawning grounds are also the salmon nurseries, providing a more protected environment than the ocean usually offers. After 2 to 6 months the eggs hatch into tiny larvae called sac fry or alevin . The alevin have a sac containing
1240-430: A healthy lamb than a golden eagle. Both species prefer native, wild prey and are unlikely to cause any extensive detriment to human livelihoods. There is one case of a bald eagle killing and feeding on an adult, pregnant ewe (then joined in eating the kill by at least 3 other eagles), which, weighing on average over 60 kg (130 lb), is much larger than any other known prey taken by this species. Supplemental prey
1364-531: A lack of human disturbance, spend their time in various upland, terrestrial habitats sometimes quite far away from waterways. In the northern half of North America (especially the interior portion), this terrestrial inhabitance by bald eagles tends to be especially prevalent because unfrozen water may not be accessible. Upland wintering habitats often consist of open habitats with concentrations of medium-sized mammals, such as prairies , meadows or tundra , or open forests with regular carrion access. The bald eagle
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#17327717468771488-455: A larger beak , straighter edged wings which are held flat (not slightly raised) and with a stiffer wing beat and feathers which do not completely cover the legs. When seen well, the golden eagle is distinctive in plumage with a more solid warm brown color than an immature bald eagle, with a reddish-golden patch to its nape and (in immature birds) a highly contrasting set of white squares on the wing. The bald eagle has sometimes been considered
1612-568: A location in the Lake and Peninsula Borough, Alaska is a stub . You can help Misplaced Pages by expanding it . Salmon run A salmon run is an annual fish migration event where many salmonid species, which are typically hatched in fresh water and live most of their adult life downstream in the ocean , swim back against the stream to the upper reaches of rivers to spawn on the gravel beds of small creeks . After spawning, all species of Pacific salmon and most Atlantic salmon die, and
1736-806: A lot of food. On Protection Island , Washington , they commonly feed on harbor seal ( Phoca vitulina ) afterbirths, still-borns and sickly seal pups. Similarly, bald eagles in Alaska readily prey on sea otter ( Enhydra lutris ) pups. Small to medium-sized terrestrial mammalian carnivores can be taken infrequently. Mustelid including American martens ( Martes pennanti ), American minks ( Neogale vison ), and larger fisher cats ( Pekania pennanti ) are known to be hunted. Foxes are also taken, including Island foxes ( Urocyon littoralis ), Arctic foxes ( Vulpes lagopus ), and grey foxes ( Urocyon cinereoargenteus ). Although fox farmers claimed that bald eagle heavily prey on young and adult free-range Arctic fox,
1860-487: A pattern of spots and vertical bars. They remain in this stage for up to three years. As they approach the time when they are ready to migrate out to the sea the parr lose their camouflage bars and undergo a process of physiological changes which allows them to survive the shift from freshwater to saltwater. At this point salmon are called smolt . Smolt spend time in the brackish waters of the river estuary while their body chemistry adjusts their osmoregulation to cope with
1984-400: A preference for bodies of water with a circumference greater than 11 km (7 mi), and lakes with an area greater than 10 km (4 sq mi) are optimal for breeding bald eagles. The bald eagle typically requires old-growth and mature stands of coniferous or hardwood trees for perching, roosting, and nesting. Tree species reportedly is less important to the eagle pair than
2108-414: A range of biota, including poor swimmers. Skilled predators, such as bears , bald eagles and fishermen can await the salmon during the run. Normally solitary animals, grizzly bears congregate by streams and rivers when the salmon spawn. Predation from harbor seals , California sea lions , and Steller sea lions can pose a significant threat, even in river ecosystems. Black bears also fish
2232-493: A record from 1876 in Wyoming County, New York of an enormous adult bald eagle that was shot and reportedly scaled 8.2 kg (18 lb). Among standard linear measurements, the wing chord is 51.5–69 cm (20.3–27.2 in), the tail is 23–37 cm (9.1–14.6 in) long, and the tarsus is 8 to 11 cm (3.1 to 4.3 in). The culmen reportedly ranges from 3 to 7.5 cm (1.2 to 3.0 in), while
2356-452: A salmon depends on the position of the standing wave or hydraulic jump at the base of the fall, as well as how deep the water is. Fish ladders , or fishways, are specially designed to help salmon and other fish to bypass dams and other man-made obstructions, and continue on to their spawning grounds further upriver. Data suggest that navigation locks have a potential to be operated as vertical slot fishways to provide increased access for
2480-482: A shallow depression. The redd may contain up to 5,000 eggs, each about the size of a pea, covering 30 square feet (2.8 m ). The eggs usually range from orange to red. One or more males will approach the female in her redd, depositing his sperm, or milt, over her eggs. The female then covers the eggs by disturbing the gravel at the upstream edge of the depression before moving on to make another redd. The female will make as many as seven redds before her supply of eggs
2604-408: A single bald eagle successfully displaced two consecutive golden eagles from a kill. Though bald eagles face few natural threats, an unusual attacker comes in the form of the common loon ( G. immer ), which is also taken by eagles as prey. While common loons normally avoid conflict, they are highly territorial and will attack predators and competitors by stabbing at them with their knife-like bill; as
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#17327717468772728-456: A spawning area will in fact survive to spawn." The eggs of a female salmon are called her roe . To lay her roe, the female salmon builds a spawning nest, called a redd , in a riffle with gravel as its streambed . A riffle is a relatively shallow length of stream where the water is turbulent and flows faster. She builds the redd by using her tail ( caudal fin ) to create a low-pressure zone, lifting gravel to be swept downstream, and excavating
2852-624: A whole food web, we like to think of them as North America's answer to the Serengeti's wildebeest . Wolves normally hunt for deer. A 2008 study suggests that when the salmon run starts, wolves choose to fish for salmon, even if plenty of deer are still available. "Selecting benign prey such as salmon makes sense from a safety point of view. While hunting deer, wolves commonly incur serious and often fatal injuries. In addition to safety benefits we determined that salmon also provides enhanced nutrition in terms of fat and energy." The upper reaches of
2976-407: Is a dynamic equilibrium, controlled by genes, between homing and straying. If the spawning grounds have a uniform high quality, then natural selection should favour the descendants that home accurately. If the spawning grounds have a variable quality, then natural selection should favour a mixture of the descendants that stray and the descendants that home accurately. Prior to the run up the river,
3100-449: Is a powerful flier, and soars on thermal convection currents. It reaches speeds of 56–70 km/h (35–43 mph) when gliding and flapping, and about 48 km/h (30 mph) while carrying fish. Its dive speed is between 120–160 km/h (75–99 mph), though it seldom dives vertically. Regarding their flying abilities, despite being morphologically less well adapted to faster flight than golden eagles (especially during dives),
3224-493: Is able to carry it away successfully. They obtain much of their food as carrion or via a practice known as kleptoparasitism , by which they steal prey away from other predators. Due to their dietary habits, bald eagles are frequently viewed in a negative light by humans. Thanks to their superior foraging ability and experience, adults are generally more likely to hunt live prey than immature eagles, which often obtain their food from scavenging. They are not very selective about
3348-487: Is because upstream freshwater bodies (especially creeks) typically do not have sufficient food available for the adult salmon diet, and they have used large amounts of energy swimming upriver, thus exhausting their own internal nutrient reserves. Spawning salmon also have programmed senescence , which is "characterized by immunosuppression and organ deterioration", making them more vulnerable to diseases. Most zombie fish die within days of spawning, but some can last up to
3472-817: Is called the salmon run. Anadromous salmon are Northern Hemisphere fish that spend their ocean phase in either the Atlantic Ocean or the Pacific Ocean . They do not thrive in warm water. There is only one species of salmon found in the Atlantic, commonly called the Atlantic salmon . These salmon run up rivers on both sides of the ocean. Seven different species of salmon inhabit the Pacific (see table), and these are collectively referred to as Pacific salmon . Five of these species run up rivers on both sides of
3596-412: Is cloudy. Likewise, electronically tagged salmon were observed to maintain direction even when swimming in water much too deep for sunlight to be of use. In 1973, it was shown that Atlantic salmon have conditioned cardiac responses to electric fields with strengths similar to those found in oceans. "This sensitivity might allow a migrating fish to align itself upstream or downstream in an ocean current in
3720-416: Is exhausted. Male pink salmon and some sockeye salmon develop pronounced humps just before they spawn. These humps may have evolved because they confer species advantages. The humps make it less likely the salmon will spawn in the shallow water at margins of the streambed, which tend to dry out during low water flows or freeze in winter. Further, riffles can contain many salmon spawning simultaneously, as in
3844-403: Is faced with two major challenges: it must supply energy suitable for swimming the river rapids, and it must supply the sperm and eggs required for the reproductive events ahead. The water in the estuary receives the freshwater discharge from the natal river. Relative to ocean water, this has a high chemical load from surface runoff . Researchers in 2009 found evidence that, as the salmon encounter
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3968-605: Is habitual mainly in Alaska) and fish-processing plants. In Southeast Alaska , fish comprise approximately 66% of the year-round diet of bald eagles and 78% of the prey brought to the nest by the parents. Eagles living in the Columbia River Estuary in Oregon were found to rely on fish for 90% of their dietary intake. At least 100 species of fish have been recorded in the bald eagle's diet. From observation in
4092-409: Is held immobile by the front toes. The beak is large and hooked, with a yellow cere . The adult bald eagle is unmistakable in its native range. The closely related African fish eagle ( Haliaeetus vocifer ) (from far outside the bald eagle's range) also has a brown body (albeit of somewhat more rufous hue), white head and tail, but differs from the bald eagle in having a white chest and black tip to
4216-506: Is mainly brown with a white head and tail. The sexes are identical in plumage , but females are about 25 percent larger than males. The yellow beak is large and hooked. The plumage of the immature is brown. The bald eagle is the national symbol of the United States of America and appears on its seal . In the late 20th century it was on the brink of extirpation in the contiguous United States. Populations have since recovered, and
4340-409: Is merely 455 g (1.003 lb) lighter in mean body mass and exceeds the bald eagle in mean wing chord length by around 3 cm (1.2 in). Additionally, the bald eagle's close cousins, the relatively longer-winged but shorter-tailed white-tailed eagle and the overall larger Steller's sea eagle ( Haliaeetus pelagicus ), may, rarely, wander to coastal Alaska from Asia. The bald eagle has
4464-418: Is moderately long and slightly wedge-shaped. Males and females are identical in plumage coloration, but sexual dimorphism is evident in the species, in that females are 25% larger than males. The beak, feet and irises are bright yellow. The legs are feather-free, and the toes are short and powerful with large talons. The highly developed talon of the hind toe is used to pierce the vital areas of prey while it
4588-504: Is now generally thought that golden eagles eat more carrion than was previously assumed). However, the two species are roughly equal in size, aggressiveness and physical strength and so competitions can go either way. Neither species is known to be dominant, and the outcome depends on the size and disposition of the individual eagles involved. Wintering bald and golden eagles in Utah both sometimes won conflicts, though in one recorded instance
4712-685: 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. In coastal New Jersey , 14 of 20 studied eagle nests included remains of turtles. The main species found were common musk turtles ( Sternotherus odoratus ), diamondback terrapin ( Malaclemys terrapin ) and juvenile common snapping turtles ( Chelydra serpentina ). In these New Jersey nests, mainly subadult and small adults were taken, ranging in carapace length from 9.2 to 17.1 cm (3.6 to 6.7 in). Similarly, many turtles were recorded in
4836-413: Is relatively easy for the much larger eagles to catch and fly with. American herring gull ( Larus smithsonianus ) are the favored avian prey species for eagles living around Lake Superior . Black ducks ( Anas rubripes ), common eiders ( Somateria mollissima ), and double-crested cormorants ( Phalacrocorax auritus ) are also frequently taken in coastal Maine and velvet scoter ( Melanitta fusca )
4960-515: Is that there are geomagnetic and chemical cues which the salmon use to guide them back to their birthplace. The fish may be sensitive to the Earth's magnetic field, which could allow the fish to orient itself in the ocean, so it can navigate back to the estuary of its natal stream. Salmon have a strong sense of smell. Speculation about whether odours provide homing cues go back to the 19th century. In 1951, Hasler hypothesised that, once in vicinity of
5084-575: The Chilkat River in Alaska has particularly good spawning grounds. Each year these attract a run of up to half a million chum salmon . As the salmon run up the river, bald eagles arrive in their thousands to feast at the spawning grounds. This results in some of the world's largest congregations of bald eagles. The number of participating eagles is directly correlated with the number of spawning salmon. Residual nutrients from salmon can also accumulate downstream in estuaries. A 2010 study suggests
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5208-598: The Greater Yellowstone area average 27 m (89 ft) high. Trees or forest used for nesting should have a canopy cover of no more than 60%, and no less than 20%, and be in close proximity to water. Most nests have been found within 200 m (660 ft) of open water. The greatest distance from open water recorded for a bald eagle nest was over 3 km (1.9 mi), in Florida. Bald eagle nests are often very large in order to compensate for size of
5332-939: The Willamette River in Portland , Oregon or John Heinz National Wildlife Refuge at Tinicum in Philadelphia , Pennsylvania, which are surrounded by a great quantity of human activity. Even more contrary to the usual sensitivity to disturbance, a family of bald eagles moved to the Harlem neighborhood in New York City in 2010. While wintering, bald eagles tend to be less habitat and disturbance sensitive. They will commonly congregate at spots with plentiful perches and waters with plentiful prey and (in northern climes) partially unfrozen waters. Alternately, non-breeding or wintering bald eagles, particularly in areas with
5456-528: The brown bullhead ( Ameiurus nebulosus ) and any species in the genus Ictalurus as well as mullet , trout , needlefish , and eels . Chain pickerels ( Esox niger ) and white suckers ( Catostomus commersonii ) are frequently taken in interior Maine . Wintering eagles on the Platte River in Nebraska preyed mainly on American gizzard shads and common carp. Bald eagles are also known to eat
5580-615: The estuary or entrance to its birth river, salmon may use chemical cues which they can smell, and which are unique to their natal stream, as a mechanism to home onto the entrance of the stream. In 1978, Hasler and his students found that the way salmon locate their home rivers with such precision was because they could recognise its characteristic smell. They further demonstrated that the smell of their river becomes imprinted in salmon when they transform into smolts, just before they migrate out to sea. Homecoming salmon can also recognise characteristic smells in tributary streams as they move up
5704-520: The salmon spawning in the area. Similar congregations of wintering bald eagles at open lakes and rivers, wherein fish are readily available for hunting or scavenging, are observed in the northern United States. It has occurred as a vagrant twice in Ireland; a juvenile was shot illegally in Fermanagh on January 11, 1973 (misidentified at first as a white-tailed eagle ), and an exhausted juvenile
5828-698: The 1950s, it was largely restricted to Alaska , the Aleutian Islands , northern and eastern Canada, and Florida. From 1966 to 2015 bald eagle numbers increased substantially throughout its winter and breeding ranges, and as of 2018 the species nests in every continental state and province in the United States and Canada. The majority of bald eagles in Canada are found along the British Columbia coast while large populations are found in
5952-473: The Chinook salmon's large size (12 to 18 kg (26 to 40 lb) average adult size) probably being taken only as carrion and a single carcass can attract several eagles. Also important in the estuaries and shallow coastlines of southern Alaska are Pacific herring ( Clupea pallasii ), Pacific sand lance ( Ammodytes hexapterus ) and eulachon ( Thaleichthys pacificus ). In Oregon's Columbia River Estuary,
6076-721: The Columbia River, 58% of the fish were caught alive by the eagle, 24% were scavenged as carcasses and 18% were pirated away from other animals. In the Pacific Northwest , spawning trout and salmon provide most of the bald eagles' diet from late summer throughout fall. Though bald eagles occasionally catch live salmon, they usually scavenge spawned salmon carcass. Southeast Alaskan eagles largely prey on pink salmon ( Oncorhynchus gorbuscha ), coho salmon ( O. kisutch ) and, more locally, sockeye salmon ( O. nerka ), with Chinook salmon ( O. tshawytscha ). Due to
6200-568: The Mother Goose Lake, headwaters of the King Salmon River. Extensive vegetation damage occurred along the flood route and Mother Goose Lake was acidified (pH of 2.9-3.1), killing all aquatic life and preventing the annual salmon run . The lake now drains from the summit through an outlet cave into Indecision Creek. Indecision Creek now usually has a strong sulphur odor, yellow color and a pH of 1.3. This article about
6324-491: The NW base of the volcano near Volcano Creek. A 400 m (1,300 ft) wide and 105 m (344 ft) deep acidified summit crater lake at Chiginagak formed after November 2004 and before May 2005. In early May 2005, a catastrophic release of acidic water from the lake, with an accompanying acidic aerosol component, drained and flooded Indecision and Volcano Creeks with acidic water, traveled 27 km downstream and flowed into
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#17327717468776448-592: The Pacific, but two species are found only on the Asian side. In the early 19th century, Chinook salmon were successfully established in the Southern Hemisphere, far from their native range, in New Zealand rivers. Attempts to establish anadromous salmon elsewhere have not succeeded. The life cycle of an anadromous salmon begins and, if it survives the full course of its natural life, usually ends in
6572-500: The absence of fixed references." In 1988, researchers found iron, in the form of single domain magnetite , resides in the skulls of sockeye salmon. The quantities present are sufficient for magnetoception . Tagging studies have shown a small number of fish do not find their natal rivers, but travel instead up other, usually nearby streams or rivers. It is important some salmon stray from their home areas; otherwise new habitats could not be colonized. In 1984, Quinn hypothesized there
6696-455: The animal kingdom's more extreme migrations , the salmon return from the saltwater ocean back to a freshwater river to spawn afresh. After several years wandering huge distances in the ocean, most surviving salmon return to the same natal rivers where they were spawned. Then most of them swim up the rivers until they reach the very spawning ground that was their original birthplace. There are various theories about how this happens. One theory
6820-454: The bald eagle is considered surprisingly maneuverable in flight. Bald eagles have also been recorded catching up to and then swooping under geese in flight, turning over and thrusting their talons into the other bird's breast. It is partially migratory, depending on location. If its territory has access to open water, it remains there year-round, but if the body of water freezes during the winter, making it impossible to obtain food, it migrates to
6944-438: The base of the tail ( caudal peduncle ) of an opponent. The physical condition of the salmon deteriorates the longer they remain in fresh water. Once the salmon have spawned, most of them deteriorate rapidly (a.k.a. "spawned out") and soon die. Some deteriorating salmon are still alive, but their bodies have already begun the process of rotting, and these deteriorating salmon are sometimes colloquially called "zombie fish". This
7068-468: The bill. The plumage of the immature is a dark brown overlaid with messy white streaking until the fifth (rarely fourth, very rarely third) year, when it reaches sexual maturity. Immature bald eagles are distinguishable from the golden eagle ( Aquila chrysaetos ), the only other very large, non-vulturine raptorial bird in North America, in that the former has a larger, more protruding head with
7192-523: The birds. The largest recorded nest was found in Florida in 1963, and was measured at nearly 10 feet wide and 20 feet deep. In Florida, nesting habitats often consist of Mangrove swamps, the shorelines of lakes and rivers, pinelands , seasonally flooded flatwoods , hardwood swamps , and open prairies and pastureland with scattered tall trees. Favored nesting trees in Florida are slash pines ( Pinus elliottii ), longleaf pines ( P. palustris ), loblolly pines ( P. taeda ) and cypress trees , but for
7316-709: The breeding season around Lake Britton in California, fish measuring 34 to 38 cm (13 to 15 in) were taken 71.8% of the time by parent eagles while fish measuring 23 to 27.5 cm (9.1 to 10.8 in) were chosen only 25% of the time. At nests around Lake Superior , the remains of fish (mostly suckers ) were found to average 35.4 cm (13.9 in) in total length. In the Columbia River estuary, most preyed on by eagles were estimated to measure less than 30 cm (12 in), but larger fish between 30 and 60 cm (12 and 24 in) or even exceeding 60 cm (24 in) in length also taken especially during
7440-602: The condition or origin, whether provided by humans, other animals, auto accidents or natural causes, of a carcass's presence, but will avoid eating carrion where disturbances from humans are a regular occurrence. They will scavenge carcasses up to the size of whales, though carcasses of ungulates and large fish are seemingly preferred. Congregated wintering waterfowl are frequently exploited for carcasses to scavenge by immature eagles in harsh winter weather. Bald eagles also may sometimes feed on material scavenged or stolen from campsites and picnics, as well as garbage dumps (dump usage
7564-1926: The consumption of the dead victims. Nine species of other accipitrids and owls are known to have been preyed upon by bald eagles. Owl prey species have ranged in size from western screech-owls ( Megascops kennicotti ) to snowy owls ( Bubo scandiacus ). Larger diurnal raptors known to have fallen victim to bald eagles have included red-tailed hawks ( Buteo jamaicensis ), peregrine falcons ( Falco peregrinus ), northern goshawks ( Accipiter gentilis ), ospreys ( Pandion haliaetus ) and black ( Coragyps atratus ) and turkey vultures ( Cathartes aura ). Mammalian 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 dogs ( Cynomys sp.) and jackrabbits ( Lepus sp.). Bald eagles in Seedskadee National Wildlife Refuge often hunt in pair to catch cottontails, jackrabbits and prairie dogs. They can attack and prey on rabbits and hares of nearly any size, from marsh rabbits ( Sylvilagus palustris ) to black and white-tailed jackrabbits ( Lepus californicus & L. townsendii ), and Arctic hares ( Lepus arcticus ). In San Luis Valley , white-tailed jackrabbits can be important prey. Additionally, rodents such as montane voles ( Microtus montanus ), brown rats ( Rattus norvegicus ), and various squirrels are taken as supplementary prey. Larger rodents such as muskrats ( Ondatra zibethicus ), young or small adult nutrias ( Myocastor coypus ) and groundhogs ( Marmota monax ) are also preyed upon. Even American porcupines ( Erethizon dorsatum ) are reportedly attacked and killed. Where available, seal colonies can provide
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#17327717468777688-492: The density and diversity of many estuarine breeding birds in the summer "were strongly predicted by salmon biomass in the autumn". Anadromous salmon provide nutrients to these "diverse assemblages ... ecologically comparable to the migrating herds of wildebeest in the Serengeti ". In 1997, researchers noted that the future of salmon runs worldwide would depend on many factors, most of which are driven by human actions. Among
7812-1439: The diet in the Chesapeake Bay . In Texas , softshell turtles are the most frequently taken prey, and a large number of Barbour's map turtles are taken in Torreya State Park . Other reptilian and amphibian prey includes southern alligator lizards ( Elgaria multicarinata ), snakes such as garter snakes and rattlesnakes , and Greater siren ( Siren lacertina ). Invertebrates are occasionally taken. In Alaska , eagles feed on sea urchins ( Strongylocentrotus sp.), chitons, mussels, and crabs. Other various mollusks such as land snails , abalones , bivalves , periwinkles , blue mussels , squids , and starfishes are taken as well. When competing for food, eagles will usually dominate other fish-eaters and scavengers, aggressively displacing mammals such as coyotes ( Canis latrans ) and foxes, and birds such as corvids , gulls , vultures and other raptors . Occasionally, coyotes, bobcats ( Lynx rufus ) and domestic dogs ( Canis familiaris ) can displace eagles from carrion, usually less confident immature birds, as has been recorded in Maine. Bald eagles are less active, bold predators than golden eagles and get relatively more of their food as carrion and from kleptoparasitism (although it
7936-528: The diet of nesting eagles, birds 28%, mammals 14% and other prey 2%. More than 400 species are known to be included in the bald eagle's prey spectrum, far more than its ecological equivalent in the Old World, the white-tailed eagle , is known to take. Despite its considerably lower population, the bald eagle may come in second amongst all North American accipitrids, slightly behind only the red-tailed hawk , in number of prey species recorded. To hunt fish,
8060-447: The eagle swoops down over the water and snatches the fish out of the water with its talons . They eat by holding the fish in one claw and tearing the flesh with the other. Eagles have structures on their toes called spicules that allow them to grasp fish. Osprey also have this adaptation. Bird prey may occasionally be attacked in flight, with prey up to the size of Canada geese attacked and killed in mid-air. It has been estimated that
8184-545: The eagle's diet is variable, depending on the quantity and availability of fish near the water's surface. Waterbirds can seasonally comprise from 7% to 80% of the prey selection for eagles in certain localities. Overall, birds are the most diverse group in the bald eagle's prey spectrum, with 200 prey species recorded. Bird species most preferred as prey by eagles tend to be medium-sized, such as western grebes ( Aechmophorus occidentalis ), mallards ( Anas platyrhynchos ), and American coots ( Fulica americana ) as such prey
8308-823: The eastern Appalachian Mountains without apparent conflict. Bald eagles are frequently mobbed by smaller raptors, due to their infrequent but unpredictable tendency to hunt other birds of prey. Many bald eagles are habitual kleptoparasites, especially in winters when fish are harder to come by. They have been recorded stealing fish from other predators such as ospreys , herons and even otters . They have also been recorded opportunistically pirating birds from peregrine falcons ( Falco peregrinus ), prairie dogs from ferruginous hawks ( Buteo regalis ) and even jackrabbits from golden eagles . When they approach scavengers such as dogs, gulls or vultures at carrion sites, they often attack them in an attempt to force them to disgorge their food. Healthy adult bald eagles are not preyed upon in
8432-536: The ecological impact they have on other wildlife is greater than would be expected in relation to their biomass . Most salmon species migrate during the autumn (September through November) , which coincides with the pre- winter activities of many hibernating animals. The annual salmon run can be a major feeding event for predators such as grizzly bears and bald eagles , as well as an important window period for sport fishermen . The post-spawning death of salmon also has important ecological consequences, because
8556-519: The fish (possibly due to overfishing) and otters (cause unknown) have had steep population declines, causing concern for seabird conservation. Because of this more extensive predation, some biologist has expressed concern that murres are heading for a "conservation collision" due to heavy eagle predation. Eagles have been confirmed to attack nocturnally active, burrow-nesting seabird species such as storm petrels and shearwaters by digging out their burrows and feeding on all animals they find inside. If
8680-709: The following fish species: rainbow trout ( Oncorhynchus mykiss ), white catfish ( Ameiurus catus ), rock greenling ( Hexagrammos lagocephalus ), Pacific cod ( Gadus macrocephalus ), Atka mackerel ( Pleurogrammus monopterygius ), largemouth bass ( Micropterus salmoides ), northern pike ( Esox lucius ), striped bass ( Morone saxatilis ), dogfish shark ( Squalidae.sp ) and Blue walleye ( Sander vitreus ). Fish taken by bald eagles varies in size, but bald eagles take larger fish than other piscivorous birds in North America, typically range from 20 to 75 cm (7.9 to 29.5 in) and prefer 36 cm (14 in) fish. When experimenters offered fish of different sizes in
8804-546: The forests of Alberta , Saskatchewan, Manitoba and Ontario . Bald eagles also congregate in certain locations in winter. From November until February, one to two thousand birds winter in Squamish, British Columbia , about halfway between Vancouver and Whistler . In March 2024, bald eagles were found nesting in Toronto for the first time. The birds primarily gather along the Squamish and Cheakamus Rivers, attracted by
8928-705: The golden eagle, with the bald species estimated to number at least 150,000 individuals, about twice as many golden eagles there are estimated to live in North America. Due to this, bald eagles often outnumber golden eagles at attractive food sources. Despite the potential for contention between these animals, in New Jersey during winter, a golden eagle and numerous bald eagles were observed to hunt snow geese alongside each other without conflict. Similarly, both eagle species have been recorded, via video-monitoring, to feed on gut piles and carcasses of white-tailed deer ( Odocoileus virginianus ) in remote forest clearings in
9052-727: The gripping power (pounds by square inch) of the bald eagle is ten times greater than that of a human. Bald eagles can fly with fish at least equal to their own weight, but if the fish is too heavy to lift, the eagle may be dragged into the water. Bald eagles are able to swim, in some cases dragging its catch ashore with its talons, but some eagles drown or succumb to hypothermia . Many sources claim that bald eagles, like all large eagles, cannot normally take flight carrying prey more than half of their own weight unless aided by favorable wind conditions. On numerous occasions, when large prey such as large fish including mature salmon or geese are attacked, eagles have been seen to make contact and then drag
9176-407: The ground. In a more typical tree standing on dry ground, nests may be located from 16 to 38 m (52 to 125 ft) in height. In Chesapeake Bay , nesting trees averaged 82 cm (32 in) in diameter and 28 m (92 ft) in total height, while in Florida, the average nesting tree stands 23 m (75 ft) high and is 23 cm (9.1 in) in diameter. Trees used for nesting in
9300-574: The higher salt levels they will encounter in the ocean. Smolt also grow the silvery scales which visually confuse ocean predators. When they have matured sufficiently in late spring, and are about 15 to 20 centimetres long, the smolt swim out of the rivers and into the sea. There they spend their first year as a post-smolt . Post-smolt form schools with other post-smolt, and set off to find deep-sea feeding grounds. They then spend up to four more years as adult ocean salmon while their full swimming ability and reproductive capacity develop. Then, in one of
9424-439: The image on the right. Predators, such as bears, will be more likely to catch the more visually prominent humped males, with their humps projecting above the surface of the water. This may provide a protective buffer for the females. Dominant male salmon defend their redds by rushing at and chasing intruders. They butt and bite them with the canine-like teeth they developed for the spawning event. The kypes are used to clamp around
9548-805: The key driving factors are (1) harvest of salmon by commercial, recreational, and subsistence fishing, (2) alterations in stream and river channels, including construction of dikes and other riparian corridor modifications, (3) electricity generation, flood control, and irrigation supplied by dams, (4) alteration by humans of freshwater, estuarine, and marine environments used by salmon, coupled with aquatic changes due to climate and ocean circulatory regimes, (5) water withdrawals from rivers and reservoirs for agricultural, municipal, or commercial purposes, (6) changes in climate caused at least in part by human activities, (7) competition from non-native fishes, (8) salmon predation by marine mammals, birds, and other fish species, (9) diseases and parasites, including those from outside
9672-558: The kills secondarily. Once North Pacific salmon die off after spawning, usually local bald eagles eat salmon carcasses almost exclusively. Eagles in Washington need to consume 489 g (1.078 lb) of fish each day for survival, with adults generally consuming more than juveniles and thus reducing potential energy deficiency and increasing survival during winter. Behind fish, the next most significant prey base for bald eagles are other waterbirds . The contribution of such birds to
9796-899: The largest subspecies ( Branta canadensis maxima ) has been reported. Other large waterbird prey include common loons ( Gavia immer ) of all ages. Large wading birds can also fall prey to bald eagles. For the great blue herons ( Ardea herodias ), bald eagles are their only serious enemies of all ages. Slightly larger Sandhill cranes ( Grus canadensis ) can be taken as well. While adult whooping cranes ( Grus americana ) are too large and formidable, their chicks can fall prey to bald eagles. They even occasionally prey on adult tundra swans ( Cygnus columbianus ). Young trumpeter swans ( Cygnus buccinator ) are also taken, and an unsuccessful attack on an adult swan has been photographed. Bald eagles have been occasionally recorded as killing other raptors . In some cases, these may be attacks of competition or kleptoparasitism on rival species but end with
9920-485: The largest true raptor ( accipitrid ) in North America. The only larger species of raptor-like bird is the California condor ( Gymnogyps californianus ), a New World vulture which today is not generally considered a taxonomic ally of true accipitrids. However, the golden eagle, averaging 4.18 kg (9.2 lb) and 63 cm (25 in) in wing chord length in its American race ( Aquila chrysaetos canadensis ),
10044-449: The main river. They may also be sensitive to characteristic pheromones given off by juvenile conspecifics . There is evidence that they can "discriminate between two populations of their own species". The recognition that each river and tributary has its own characteristic smell, and the role this plays as a navigation aid, led to a widespread search for a mechanism or mechanisms that might allow salmon to navigate over long distances in
10168-517: The measurement from the gape to the tip of the bill is 7–9 cm (2.8–3.5 in). The bill size is unusually variable: Alaskan eagles can have up to twice the bill length of birds from the southern United States ( Georgia , Louisiana , Florida), with means including both sexes of 6.83 cm (2.69 in) and 4.12 cm (1.62 in) in culmen length, respectively, from these two areas. The call consists of weak staccato, chirping whistles, kleek kik ik ik ik , somewhat similar in cadence to
10292-556: The most significant prey species were largescale suckers ( Catostomus macrocheilus ) (17.3% of the prey selected there), American shad ( Alosa sapidissima ; 13%) and common carp ( Cyprinus carpio ; 10.8%). Eagles living in the Chesapeake Bay in Maryland were found to subsist largely on American gizzard shad ( Dorosoma cepedianum ), threadfin shad ( Dorosoma petenense ) and white bass ( Morone chrysops ). Floridian eagles have been reported to prey on catfish , most prevalently
10416-894: The natal river where they were born, and even to the very spawning ground of their birth. It is thought that, when they are in the ocean, they use magnetoreception to locate the general position of their natal river, and once close to the river, that they use their sense of smell to home in on the river entrance and even their natal spawning ground. Trout , which are sister species of salmon, also perform similar migrations, although they mostly move potamodromously between creeks and large freshwater lakes, except for some coastal/ estuary subspecies such as steelhead and sea trout that migrate seasonally between salty / brackish and fresh water just like salmon do. There are also landlocked populations of some salmon species that have adapted to spend their entire life in freshwater like trout. In Northwest America , salmons are keystone species , which means
10540-650: The native region, and (10) reduced nutrient replenishment from decomposing salmon. In 2009, NOAA advised that continued runoff into North American rivers of three widely used pesticides containing neurotoxins would "jeopardize the continued existence" of endangered and threatened Pacific salmon. Global warming could see the end of some salmon runs by the end of the century, such as the Californian runs of Chinook salmon. A 2010 United Nations report said that increases in acidification of oceans would mean that shellfish such as pteropods , an important component of
10664-599: The nesting trees used by eagles, followed by hemlocks ( Tsuga ) at 20%. Increasingly, eagles nest in human-made reservoirs stocked with fish. The bald eagle is usually quite sensitive to human activity while nesting, and is found most commonly in areas with minimal human disturbance. It chooses sites more than 1.2 km (0.75 mi) from low-density human disturbance and more than 1.8 km (1.1 mi) from medium- to high-density human disturbance. However, bald eagles will occasionally nest in large estuaries or secluded groves within major cities, such as Hardtack Island on
10788-518: The night because their black fur is easily spotted by salmon in the daytime. In 2009, researchers compared the foraging success of black bears with the white-coated Kermode bear , a morphed subspecies of the black bear. They found the Kermode bear had no more success catching salmon at night time, but had greater success than the black bears during the day. Otters are also common predators. In 2011, researchers showed that when otters predate salmon,
10912-567: The non-breeding seasons. They can take fish up to at least twice their own weight, such as large mature salmons , carps , or even muskellunge ( Esox masquinongy ), by dragging its catch with talons and pull toward ashore. Much larger marine fish such as Pacific halibut ( Hippoglossus stenolepis ) and lemon sharks ( Negaprion brevirostris ) have been recorded among bald eagle prey though probably are only taken as young, as small, newly mature fish, or as carrion. Benthic fishes such as catfish are usually consumed after they die and float to
11036-541: The ocean salmon diet, would be finding it more difficult to build their aragonite shells. There were concerns that this too could endanger future salmon runs. In a 1982 video game called Salmon Run , the player takes the role of Sam the Salmon, swimming upriver to mate. Along the way he encounters waterfalls, a bear, fishermen, and seagulls. In the Disney animated feature film, Brother Bear , Kenai and Koda reached
11160-653: The ocean where they can recover and spawn again the next season. In the Pacific Northwest and Alaska, salmon is a keystone species , supporting wildlife from birds to bears and otters. The bodies of salmon represent a transfer of nutrients from the ocean, rich in nitrogen, sulfur, carbon and phosphorus, to the forest ecosystem . Grizzly bears function as ecosystem engineers , capturing salmon and carrying them into adjacent wooded areas. There they deposit nutrient-rich urine and faeces and partially eaten carcasses. It has been estimated that bears leave up to half
11284-413: The ocean. They need high swimming and leaping abilities to battle the rapids and other obstacles the river may present, and they need a full sexual development to ensure a successful spawn at the end of the run. All their energy goes into the physical rigours of the journey and the dramatic morphological transformations they must still complete before they are ready for the spawning events ahead. The run up
11408-411: The open ocean. In 1977, Leggett identified, as mechanisms worth investigating, the use of the sun for navigation, and orientation to various possible gradients, such as temperature, salinity or chemicals gradients, or geomagnetic or geoelectric fields. There is little evidence salmon use clues from the sun for navigation. Migrating salmon have been observed maintaining direction at nighttime and when it
11532-449: The other comes behind it in order to ambush it. While hunting waterfowl, bald eagles repeatedly fly at a target and cause it to dive repeatedly, hoping to exhaust the victim so it can be caught (white-tailed eagles have been recorded hunting waterfowl in the same way). When hunting concentrated prey, a successful catch often results in the hunting eagle being pursued by other eagles and needing to find an isolated perch for consumption if it
11656-678: The predation events are sporadic. In one instance, two bald Eagles fed upon a red fox ( Vulpes vulpes ) that had tried to cross a frozen Delaware Lake . Other medium-sized carnivorans such as striped skunks ( Mephitis mephitis ), American hog-nosed skunks ( Conepatus leuconotus ), and common raccoons ( Procyon lotor ) are taken, as well as domestic cats ( Felis catus ) and dogs ( canis familiaris ). Other wild mammalian prey include fawns of deer such as white-tailed deer ( Odocoileus virginianus ) and Sitka deer ( Odocoileus hemionus sitkensis ), which weigh around 3 kg (6.6 lb) can be taken alive by bald eagles. In one instance,
11780-527: The prey in a strenuously labored, low flight over the water to a bank, where they then finish off and dismember the prey. When food is abundant, an eagle can gorge itself by storing up to 1 kg (2.2 lb) of food in a pouch in the throat called a crop. Gorging allows the bird to fast for several days if food becomes unavailable. Occasionally, bald eagles may hunt cooperatively when confronting prey, especially relatively large prey such as jackrabbits or herons, with one bird distracting potential prey, while
11904-403: The range of the bald eagle has increased following conservation efforts, these interactions have been observed on several occasions, including a fatality of a bald eagle in Maine that is presumed to have come about as a result of it attacking a nest, then having a fatal puncture wound inflicted by one or both loon parents. The bald eagle is thought to be much more numerous in North America than
12028-408: The remainder of the yolk, and they stay hidden in the gravel while they feed on the yolk. When the yolk has gone they must find food for themselves, so they leave the protection of the gravel and start feeding on plankton . At this point the baby salmon are called fry . At the end of the summer the fry develop into juvenile fish called parr . Parr feed on small invertebrates and are camouflaged with
12152-420: The resulting drop in salinity and increase in olfactory stimulation, two key metabolic changes are triggered: there is a switch from using red muscles for swimming to using white muscles, and there is an increase in the sperm and egg load. "Pheromones at the spawning grounds [trigger] a second shift to further enhance reproductive loading." The salmon also undergo radical morphological changes as they prepare for
12276-513: The riparian zones the salmon reach. The nutrients can also be washed downstream into estuaries where they accumulate and provide significant support for invertebrates and estuarine-breeding waterbirds . Most salmon are anadromous , a term which comes from the Greek anadromos , meaning "running upward". Anadromous fish grow up mostly in the saltwater in oceans. When they have matured they migrate or "run up" freshwater rivers to spawn in what
12400-604: The river can be exhausting, sometimes requiring the salmon to battle hundreds of miles upstream against strong currents and rapids. They cease feeding during the run. Chinook and sockeye salmon from central Idaho must travel 900 miles (1,400 km) and climb nearly 7,000 feet (2,100 m) before they are ready to spawn. Salmon deaths that occur on the upriver journey are referred to as en route mortality . Salmon negotiate waterfalls and rapids by leaping or jumping. They have been recorded making vertical jumps as high as 3.65 metres (12 ft). The height that can be achieved by
12524-399: The salmon life cycle starts over again with the new generation of hatchlings . Salmon are anadromous , spending their juvenile life in rivers or lakes, and then migrating out to sea where they spend adult lives and gain most of their body mass . When they reach sexual maturity , the adults return to the upstream rivers to reproduce . Usually they return with uncanny precision to
12648-634: The salmon can "sniff them out". They demonstrated that once otters have eaten salmon, the remaining salmon could detect and avoid the waters where otter faeces was present. The term prespawn mortality is used to refer to fish that arrive successfully at the spawning grounds, and then die without spawning. Prespawn mortality is surprisingly variable, with one study observing rates between 3% and 90%. Factors that contribute to these mortalities include high temperatures, high river discharge rates, and parasites and diseases. "At present there are no reliable indicators to predict whether an individual arriving at
12772-573: The salmon run and met a large group of bears led by Tug at the Annual Salmon Run. Featuring the song " Welcome " by The Blind Boys of Alabama and Phil Collins . Bald eagle Falco pygargus Daudin, 1800 (nec Linnaeus) Falco ossifragus Shaw, 1809 (nec Linnaeus) The bald eagle ( Haliaeetus leucocephalus ) is a bird of prey found in North America . A sea eagle , it has two known subspecies and forms
12896-546: The salmon they harvest on the forest floor, in densities that can reach 4,000 kilograms per hectare, providing as much as 24% of the total nitrogen available to the riparian woodlands. The foliage of spruce trees up to 500 m (1,600 ft) from a stream where grizzlies fish salmon have been found to contain nitrogen originating from fished salmon. Salmon continue to surprise us, showing us new ways in which their oceanic migrations eventually permeate entire terrestrial ecosystems. In terms of providing food and nutrients to
13020-409: The salmon undergo profound physiological changes. Fish swim by contracting longitudinal red muscle and obliquely oriented white muscles. Red muscles are used for sustained activity, such as ocean migrations. White muscles are used for bursts of activity, such as bursts of speed or jumping. As the salmon comes to end of its ocean migration and enters the estuary of its natal river, its energy metabolism
13144-456: The salmon. Black bears usually operate during the day, but when it comes to salmon they tend to fish at night. This is partly to avoid competition with the more powerful brown bears, but it is also because they catch more salmon at night. During the day, salmon are very evasive and attuned to visual clues, but at night they focus on their spawning activities, generating acoustic clues the bears tune into. Black bears may also fish for salmon during
13268-545: The same ecological niche in their respective ranges. The pair diverged from other sea eagles at the beginning of the Early Miocene (c. 10 Ma BP ) at the latest, but possibly as early as the Early/Middle Oligocene , 28 Ma BP, if the most ancient fossil record is correctly assigned to this genus . The plumage of an adult bald eagle is evenly dark brown with a white head and tail. The tail
13392-400: The significant nutrients in their carcasses , rich in nitrogen , sulfur , carbon and phosphorus , are transferred from the ocean and released to inland aquatic ecosystems , terrestrial animals (such as bears) and the wetlands and riparian woodlands adjacent to the rivers. This has knock-on effects not only for the next generation of salmon, but to every wildlife species living in
13516-553: The single reproductive event of semelparous organisms is usually large and fatal to the spawners. It is an evolutionary strategy that concentrates all available resources into maximizing reproduction, at the expense of individual organism's life, which is common among insects but rare among vertebrates . All six species of Pacific salmons live for many years in the ocean before swimming to the freshwater stream of its birth, spawning, and then dying. Most Atlantic salmon also die after spawning, but about 5 to 10% (mostly female) return to
13640-409: The south or to the coast. A number of populations are subject to post-breeding dispersal, mainly in juveniles; Florida eagles, for example, will disperse northwards in the summer. The bald eagle selects migration routes which take advantage of thermals , updrafts , and food resources. During migration, it may ascend in a thermal and then glide down, or may ascend in updrafts created by the wind against
13764-448: The southern coastal areas where mangroves are usually used. In Wyoming , groves of mature cottonwoods or tall pines found along streams and rivers are typical bald eagle nesting habitats. Wyoming eagles may inhabit habitat types ranging from large, old-growth stands of ponderosa pines ( Pinus ponderosa ) to narrow strips of riparian trees surrounded by rangeland. In Southeast Alaska , Sitka spruce ( Picea sitchensis ) provided 78% of
13888-421: The spawning event ahead. All salmon lose the silvery blue they had as ocean fish, and their colour darkens, sometimes with a radical change in hue. Salmon are sexually dimorphic , and the male salmon develop canine-like teeth and their jaws develop a pronounced curve or hook ( kype ). Some species of male salmon grow large humps. Salmon start the run in peak condition, the culmination of years of development in
14012-575: The species increases in size further away from the equator and the tropics. For example, eagles from South Carolina average 3.27 kg (7.2 lb) in mass and 1.88 m (6 ft 2 in) in wingspan, smaller than their northern counterparts. One field guide in Florida listed similarly small sizes for bald eagles there, at about 4.13 kg (9.1 lb). Of intermediate size, 117 migrant bald eagles in Glacier National Park were found to average 4.22 kg (9.3 lb) but this
14136-486: The species' status was upgraded from " endangered " to " threatened " in 1995 and removed from the list altogether in 2007. The bald eagle is placed in the genus Haliaeetus ( sea eagles ), and gets both its common and specific scientific names from the distinctive appearance of the adult's head. Bald in the English name is from an older usage meaning "having white on the face or head" rather than "hairless", referring to
14260-473: The surface, though while temporarily swimming in the open may be more vulnerable to predation than most fish since their eyes focus downwards. Bald eagles also regularly exploit water turbines which produce battered, stunned or dead fish easily consumed. Predators who leave behind scraps of dead fish that they kill, such as brown bears ( Ursus arctos ), gray wolves ( Canis lupus ) and red foxes ( Vulpes vulpes ), may be habitually followed in order to scavenge
14384-436: The tree's height, composition and location. Perhaps of paramount importance for this species is an abundance of comparatively large trees surrounding the body of water. Selected trees must have good visibility, be over 20 m (66 ft) tall, an open structure, and proximity to prey. If nesting trees are in standing water such as in a mangrove swamp, the nest can be located fairly low, at as low as 6 m (20 ft) above
14508-429: The water with its talons. It builds the largest nest of any North American bird and the largest tree nests ever recorded for any animal species, up to 4 m (13 ft) deep, 2.5 m (8.2 ft) wide, and 1 metric ton (1.1 short tons) in weight. Sexual maturity is attained at the age of four to five years. Bald eagles are not bald ; the name derives from an older meaning of the word, "white headed". The adult
14632-498: The white head feathers contrasting with the darker body. The genus name is Neo-Latin : Haliaeetus (from the Ancient Greek : ἁλιάετος , romanized : haliaetos , lit. 'sea eagle'), and the specific name, leucocephalus , is Latinized ( Ancient Greek : λευκός , romanized : leukos , lit. 'white') and ( κεφαλή , kephalḗ , 'head'). The bald eagle
14756-526: The wild and are thus considered apex predators . 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. Bald eagle courtship involves elaborate, spectacular calls and flight displays by
14880-411: The wings. A survey of adult weights in Alaska showed that females there weighed on average 5.35 kg (11.8 lb), respectively, and males weighed 4.23 kg (9.3 lb) against immatures which averaged 5.09 kg (11.2 lb) and 4.05 kg (8.9 lb) in the two sexes. An Alaskan adult female eagle that was considered outsized weighed some 7.4 kg (16 lb). R.S. Palmer listed
15004-542: Was captured near Castleisland , County Kerry on November 15, 1987. There is also a record of it from Llyn Coron, Anglesey, in the United Kingdom, from October 17, 1978; the provenance of this individual eagle has remained in dispute. The bald eagle occurs during its breeding season in virtually any kind of American wetland habitat such as seacoasts , rivers, large lakes or marshes or other large bodies of open water with an abundance of fish. Studies have shown
15128-651: Was dominant prey in San Miguel Island . Due to easy accessibility and lack of formidable nest defense against eagles by such species, bald eagles are capable of preying on such seabirds at all ages, from eggs to mature adults, and they can effectively cull large portions of a colony. Along some portions of the North Pacific coastline, bald eagles which had historically preyed mainly kelp -dwelling fish and supplementally sea otter ( Enhydra lutris ) pups are now preying mainly on seabird colonies since both
15252-542: Was mostly (possibly post-dispersal) juvenile eagles, with 6 adults here averaging 4.3 kg (9.5 lb). Wintering eagles in Arizona (winter weights are usually the highest of the year since, like many raptors, they spend the highest percentage of time foraging during winter) were found to average 4.74 kg (10.4 lb). The largest eagles are from Alaska , where large females may weigh more than 7 kg (15 lb) and span 2.44 m (8 ft 0 in) across
15376-482: Was one of the many species originally described by Carl Linnaeus in his 18th-century work Systema Naturae , under the name Falco leucocephalus . There are two recognized subspecies of bald eagle: The bald eagle forms a species pair with the white-tailed eagle of Eurasia . This species pair consists of a white-headed and a tan-headed species of roughly equal size; the white-tailed eagle also has overall somewhat paler brown body plumage. The two species fill
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