Steller's Sea Eagle
Encyclopedia
The Steller's Sea Eagle, Haliaeetus pelagicus, is a large bird of prey
in the family Accipitridae
. It lives in coastal northeastern Asia and mainly preys on fish
. It is, on average, the heaviest eagle in the world, at about 4.9 kg (10.8 lb; 0.771617917647072 st), but often lags behind the Harpy Eagle and Philippine Eagle
in other measurements. This bird is named after the German naturalist Georg Wilhelm Steller
.
Haliaeetus and is one of the largest raptors
overall. The typical size range is 85 to 105 cm (33.5 to 41.3 in) long and the wingspan is 1.95 to 2.5 m (6.4 to 8.2 ft). Females typically weigh from 6.8 kg (15 lb; 1.1 st), while males are considerably lighter with a weight range from 4.9 kg (10.8 lb; 0.771617917647072 st). An unverified record exists of a huge female, who apparently gorged on salmon, having weighed 12.7 kg (28 lb; 2 st).
Two subspecies
have been named: The relatively widespread nominate pelagicus and the virtually unknown H. p. niger. The latter name was given to the population which lacked white feathers except for the tail and supposedly was resident all year in Korea
. Last seen in 1968 and long believed to be extinct, a female matching H. p. niger in appearance was born in captivity in 2001. Both its parent were "normal" in appearance, indicating that H. p. niger is an extremely rare morph rather than a valid subspecies, as had already been suggested earlier.
The relationships of Steller's Sea-eagle are not completely resolved. mtDNA cytochrome b
sequence
data tentatively suggests that this species's ancestors diverged early in the colonization of the Holarctic
by sea eagles. This is strongly supported by morphological
traits such as the yellow eyes, beak, and talons shared by this species and the other northern sea-eagles, the White-tailed
and Bald Eagle
s, and biogeography
. It is unique among all sea eagles in having a yellow bill
even in juvenile birds, and possessing 14, not 12, rectrices. The skull (at about 14.6 cm (5.7 in)) and bill are the largest of any eagle and comparable in size to the largest Old World vulture
s, the biggest accipitrids.
, the coastal area around the Sea of Okhotsk
, the lower reaches of the Amur river and on northern Sakhalin
and the Shantar Islands
, Russia
. The majority of birds winter farther south, in the southern Kuril islands
, Russia
and Hokkaidō
, Japan
. That being said, the Steller's Sea-eagle is less vagrant
than the White-tailed Eagle
, usually lacking the long-range dispersal common in juveniles of that species
.
The large body size (see also Bergmann's Rule
) suggests that it is a glacial relict
, meaning that it evolved in a narrow subarctic
zone of the northeasternmost Asia
n coasts, which shifted its latitude
according to ice age
cycles, and never occurred anywhere else.
Vagrant eagles have been found in North America
and Taiwan
but these are considered to be individual eagles that have strayed from the species' typical range.
This bird nests in two habitats: along sea coasts and in large rivers with mature trees. They nest on large, rocky outcroppings or at the tops of large trees. Migrating Steller's sea eagles winter along rivers in Japan and occasionally move to mountainous inland areas as opposed to the sea coast. They are also occasionally seen over and perching on sea ice in northern waters.
. Favored prey include salmon
(Onchorhynchus spp.), trout
and cod
. Like most Haliaeetus eagles, they hunt fish almost exclusively in shallow water. Relatively large numbers of these normally solitary birds can be seen congregating on particularly productive spawning rivers due to an abundant food supply. Besides fish, it also preys on water-dwelling birds (including duck
s, geese, swan
s, crane
s, heron
s and gull
s), various mammals, crab
s, mussel
s, squid
and carrion
. Along the sea coast, water birds are the most commonly caught prey. Among bird prey, this eagle has shown a strong local preference for Slaty-backed Gull
s. This eagle has been recorded preying occasionally on young seals
. It was estimated in one study (Brown & Amaden), that some seal pups carried off in flight by the eagles weighed at least 9.1 kg (20 lbs), which (if true) would be the greatest load carrying ever known for a bird; however the preys' weights were not verified.
builds several aeries (height, 150 cm; diameter up to 250 cm) high up on tree
s and rock
. It is possible that the eagles change occasionally between these nest
s.
After courtship
, which usually occurs between February and March, the animals lay their first white-green egg
s around April to May. Usually only one chick survives. After an incubation
period of around 39 – 45 days the chicks hatch, having ash grey to white down
. As young birds the down changes to brown feathers and at an age of around ten weeks, the young birds learn to fly. They reach sexual maturity
at around four to five years. Full adult
plumage
in the Steller's Sea Eagle only appears at age eight to ten years.
Eggs and nestlings can be preyed on by arboreal mammals, such as marten
s, and birds, usually corvids. In one case, a brown bear
was able to access a nest and ate the nestlings contained in it. Once fully grown, the eagle has no natural predators.
by the IUCN. The main threats to its survival are habitat alteration, industrial pollution
and over-fishing. The current population is estimated at 5,000 and decreasing. It was observed that recent heavy flooding, which may have been an effect of global climate change
, caused almost complete nesting failure for the eagles nesting in Russia
n rivers due to completely hampering the ability of the parents to capture the fish essential to their nestlings' survival. Due to a lack of other accessable prey in some areas, increasingly eagles on Hokkaido
have moved inland and scavenged on sika deer
carcasses left by hunters, exposing them to a risk of lead poisoning through ingestion of lead shot.
}}
Cited works
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
in the family Accipitridae
Accipitridae
The Accipitridae, one of the two major families within the order Accipitriformes , are a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a...
. It lives in coastal northeastern Asia and mainly preys on fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
. It is, on average, the heaviest eagle in the world, at about 4.9 kg (10.8 lb; 0.771617917647072 st), but often lags behind the Harpy Eagle and Philippine Eagle
Philippine Eagle
The Philippine Eagle , also known as the Monkey-eating Eagle, is an eagle of the family Accipitridae that is endemic to forests in the Philippines. It has brown and white-coloured plumage, and a shaggy crest, and generally measures in length and weighs...
in other measurements. This bird is named after the German naturalist Georg Wilhelm Steller
Georg Wilhelm Steller
Georg Wilhelm Steller was a German botanist, zoologist, physician and explorer, who worked in Russia and is considered the discoverer of Alaska and a pioneer of Alaskan natural history.-Biography:...
.
Description, systematics, and status
Steller's Sea-eagle is the biggest bird in the genusGenus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Haliaeetus and is one of the largest raptors
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
overall. The typical size range is 85 to 105 cm (33.5 to 41.3 in) long and the wingspan is 1.95 to 2.5 m (6.4 to 8.2 ft). Females typically weigh from 6.8 kg (15 lb; 1.1 st), while males are considerably lighter with a weight range from 4.9 kg (10.8 lb; 0.771617917647072 st). An unverified record exists of a huge female, who apparently gorged on salmon, having weighed 12.7 kg (28 lb; 2 st).
Two subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
have been named: The relatively widespread nominate pelagicus and the virtually unknown H. p. niger. The latter name was given to the population which lacked white feathers except for the tail and supposedly was resident all year in Korea
Korea
Korea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...
. Last seen in 1968 and long believed to be extinct, a female matching H. p. niger in appearance was born in captivity in 2001. Both its parent were "normal" in appearance, indicating that H. p. niger is an extremely rare morph rather than a valid subspecies, as had already been suggested earlier.
The relationships of Steller's Sea-eagle are not completely resolved. mtDNA cytochrome b
Cytochrome b
Cytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
data tentatively suggests that this species's ancestors diverged early in the colonization of the Holarctic
Holarctic
The Holarctic ecozone refers to the habitats found throughout the northern continents of the world as a whole. This region is divided into the Palearctic, consisting of Northern Africa and all of Eurasia, with the exception of Southeast Asia and the Indian subcontinent, and the Nearctic,...
by sea eagles. This is strongly supported by morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
traits such as the yellow eyes, beak, and talons shared by this species and the other northern sea-eagles, the White-tailed
White-tailed Eagle
The White-tailed Eagle , also known as the Sea Eagle, Erne , or White-tailed Sea-eagle, is a large bird of prey in the family Accipitridae which includes other raptors such as hawks, kites, and harriers...
and Bald Eagle
Bald Eagle
The Bald Eagle is a bird of prey found in North America. It is the national bird and symbol of the United States of America. This sea eagle has two known sub-species and forms a species pair with the White-tailed Eagle...
s, and biogeography
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...
. It is unique among all sea eagles in having a yellow bill
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
even in juvenile birds, and possessing 14, not 12, rectrices. The skull (at about 14.6 cm (5.7 in)) and bill are the largest of any eagle and comparable in size to the largest Old World vulture
Old World vulture
Old World vultures belong to the family Accipitridae, which also includes eagles, buzzards, kites, and hawks.Old World vultures are not closely related to the superficially similar New World vultures and condors, and do not share that group's good sense of smell. The similarities between the two...
s, the biggest accipitrids.
Distribution and habitat
Steller's Sea Eagle breeds on the Kamchatka PeninsulaKamchatka Peninsula
The Kamchatka Peninsula is a peninsula in the Russian Far East, with an area of . It lies between the Pacific Ocean to the east and the Sea of Okhotsk to the west...
, the coastal area around the Sea of Okhotsk
Sea of Okhotsk
The Sea of Okhotsk is a marginal sea of the western Pacific Ocean, lying between the Kamchatka Peninsula on the east, the Kuril Islands on the southeast, the island of Hokkaidō to the far south, the island of Sakhalin along the west, and a long stretch of eastern Siberian coast along the west and...
, the lower reaches of the Amur river and on northern Sakhalin
Sakhalin
Sakhalin or Saghalien, is a large island in the North Pacific, lying between 45°50' and 54°24' N.It is part of Russia, and is Russia's largest island, and is administered as part of Sakhalin Oblast...
and the Shantar Islands
Shantar Islands
The Shantar Islands are a group of fifteen islands that lie in Uda Bay, in the southwestern zone of the Sea of Okhotsk. These islands are located close to the shores of the Siberian mainland...
, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
. The majority of birds winter farther south, in the southern Kuril islands
Kuril Islands
The Kuril Islands , in Russia's Sakhalin Oblast region, form a volcanic archipelago that stretches approximately northeast from Hokkaidō, Japan, to Kamchatka, Russia, separating the Sea of Okhotsk from the North Pacific Ocean. There are 56 islands and many more minor rocks. It consists of Greater...
, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
and Hokkaidō
Hokkaido
, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island; it is also the largest and northernmost of Japan's 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaido from Honshu, although the two islands are connected by the underwater railway Seikan Tunnel...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. That being said, the Steller's Sea-eagle is less vagrant
Vagrancy (biology)
Vagrancy is a phenomenon in biology whereby individual animals appear well outside their normal range; individual animals which exhibit vagrancy are known as vagrants. The term accidental is sometimes also used...
than the White-tailed Eagle
White-tailed Eagle
The White-tailed Eagle , also known as the Sea Eagle, Erne , or White-tailed Sea-eagle, is a large bird of prey in the family Accipitridae which includes other raptors such as hawks, kites, and harriers...
, usually lacking the long-range dispersal common in juveniles of that species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
.
The large body size (see also Bergmann's Rule
Bergmann's Rule
Bergmann's rule is an ecogeographic principle that states that within a broadly distributed genus, species of larger size are found in colder environments, and species of smaller size are found in warmer regions. Although originally formulated in terms of species within a genus, it has often been...
) suggests that it is a glacial relict
Relict
A relict is a surviving remnant of a natural phenomenon.* In biology a relict is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas....
, meaning that it evolved in a narrow subarctic
Subarctic
The Subarctic is a region in the Northern Hemisphere immediately south of the true Arctic and covering much of Alaska, Canada, the north of Scandinavia, Siberia, and northern Mongolia...
zone of the northeasternmost Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
n coasts, which shifted its latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
according to ice age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...
cycles, and never occurred anywhere else.
Vagrant eagles have been found in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
and Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
but these are considered to be individual eagles that have strayed from the species' typical range.
This bird nests in two habitats: along sea coasts and in large rivers with mature trees. They nest on large, rocky outcroppings or at the tops of large trees. Migrating Steller's sea eagles winter along rivers in Japan and occasionally move to mountainous inland areas as opposed to the sea coast. They are also occasionally seen over and perching on sea ice in northern waters.
Diet
The Steller's Sea-eagle mainly feeds on fishFish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
. Favored prey include salmon
Salmon
Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
(Onchorhynchus spp.), trout
Trout
Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...
and cod
Cod
Cod is the common name for genus Gadus, belonging to the family Gadidae, and is also used in the common name for various other fishes. Cod is a popular food with a mild flavor, low fat content and a dense, flaky white flesh. Cod livers are processed to make cod liver oil, an important source of...
. Like most Haliaeetus eagles, they hunt fish almost exclusively in shallow water. Relatively large numbers of these normally solitary birds can be seen congregating on particularly productive spawning rivers due to an abundant food supply. Besides fish, it also preys on water-dwelling birds (including duck
Duck
Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...
s, geese, swan
Swan
Swans, genus Cygnus, are birds of the family Anatidae, which also includes geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe Cygnini. Sometimes, they are considered a distinct subfamily, Cygninae...
s, crane
Crane (bird)
Cranes are a family, Gruidae, of large, long-legged and long-necked birds in the order Gruiformes. There are fifteen species of crane in four genera. Unlike the similar-looking but unrelated herons, cranes fly with necks outstretched, not pulled back...
s, heron
Heron
The herons are long-legged freshwater and coastal birds in the family Ardeidae. There are 64 recognised species in this family. Some are called "egrets" or "bitterns" instead of "heron"....
s and gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s), various mammals, crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s, mussel
Mussel
The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...
s, squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
and carrion
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
. Along the sea coast, water birds are the most commonly caught prey. Among bird prey, this eagle has shown a strong local preference for Slaty-backed Gull
Slaty-backed Gull
The Slaty-backed Gull , is a large white-headed gull that breeds on the western coast of Alaska but travels widely during nonbreeding seasons. Claims have been made as to its presence throughout North America as well as the eastern coast of Asia. It is similar in appearance to the Western Gull...
s. This eagle has been recorded preying occasionally on young seals
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...
. It was estimated in one study (Brown & Amaden), that some seal pups carried off in flight by the eagles weighed at least 9.1 kg (20 lbs), which (if true) would be the greatest load carrying ever known for a bird; however the preys' weights were not verified.
Reproduction
This eagleEagle
Eagles are members of the bird family Accipitridae, and belong to several genera which are not necessarily closely related to each other. Most of the more than 60 species occur in Eurasia and Africa. Outside this area, just two species can be found in the United States and Canada, nine more in...
builds several aeries (height, 150 cm; diameter up to 250 cm) high up on tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s and rock
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
. It is possible that the eagles change occasionally between these nest
Bird nest
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American Robin or Eurasian Blackbird, or the elaborately woven hanging nest of the...
s.
After courtship
Courtship
Courtship is the period in a couple's relationship which precedes their engagement and marriage, or establishment of an agreed relationship of a more enduring kind. In courtship, a couple get to know each other and decide if there will be an engagement or other such agreement...
, which usually occurs between February and March, the animals lay their first white-green egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
s around April to May. Usually only one chick survives. After an incubation
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...
period of around 39 – 45 days the chicks hatch, having ash grey to white down
Down feather
The down of birds is a layer of fine feathers found under the tougher exterior feathers. Very young birds are clad only in down. Powder down is a specialized type of down found only in a few groups of birds. Down is a fine thermal insulator and padding, used in goods such as jackets, bedding,...
. As young birds the down changes to brown feathers and at an age of around ten weeks, the young birds learn to fly. They reach sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at around four to five years. Full adult
Adult
An adult is a human being or living organism that is of relatively mature age, typically associated with sexual maturity and the attainment of reproductive age....
plumage
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
in the Steller's Sea Eagle only appears at age eight to ten years.
Eggs and nestlings can be preyed on by arboreal mammals, such as marten
Marten
The martens constitute the genus Martes within the subfamily Mustelinae, in family Mustelidae.-Description:Martens are slender, agile animals, adapted to living in taigas, and are found in coniferous and northern deciduous forests across the northern hemisphere. They have bushy tails, and large...
s, and birds, usually corvids. In one case, a brown bear
Brown Bear
The brown bear is a large bear distributed across much of northern Eurasia and North America. It can weigh from and its largest subspecies, the Kodiak Bear, rivals the polar bear as the largest member of the bear family and as the largest land-based predator.There are several recognized...
was able to access a nest and ate the nestlings contained in it. Once fully grown, the eagle has no natural predators.
Conservation status
This species is classified as VulnerableVulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
by the IUCN. The main threats to its survival are habitat alteration, industrial pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
and over-fishing. The current population is estimated at 5,000 and decreasing. It was observed that recent heavy flooding, which may have been an effect of global climate change
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
, caused almost complete nesting failure for the eagles nesting in Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
n rivers due to completely hampering the ability of the parents to capture the fish essential to their nestlings' survival. Due to a lack of other accessable prey in some areas, increasingly eagles on Hokkaido
Hokkaido
, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island; it is also the largest and northernmost of Japan's 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaido from Honshu, although the two islands are connected by the underwater railway Seikan Tunnel...
have moved inland and scavenged on sika deer
Sika Deer
The Sika Deer, Cervus nippon, also known as the Spotted Deer or the Japanese Deer, is a species of deer native to much of East Asia and introduced to various other parts of the world...
carcasses left by hunters, exposing them to a risk of lead poisoning through ingestion of lead shot.
Footnotes
References}}
Cited works
- Brown, Leslie Hilton (1976): Eagles of the world. David & Charles, Newton Abbot. ISBN 0-7153-7269-6
- Ferguson-Lees, James; Christie, David A. & Franklin, Kim (2005): Raptors of the world: a field guide. Christopher HelmHelm Identification GuidesThe Helm Identification Guides are a series of books that identify groups of birds. The series include two types of guides, those that are:* Taxonomic, dealing with a particular family of birds on a worldwide scale—most early Helm Guides were this type, as well as many more-recent ones,...
, London & Princeton. ISBN 0-7136-6957-8 - True, Dan (1980): A family of eagles. Everest, New York. ISBN 0-89696-078-1
External links
- BirdLife Species Factsheet. Retrieved 2006-DEC-01.
- Biocrawler.com: http://www.biocrawler.com/videos/displayimage.php?album=10&pos=2Windows MediaWindows MediaWindows Media is a multimedia framework for media creation and distribution for Microsoft Windows. It consists of a software development kit with several application programming interfaces and a number of prebuilt technologies, and is the replacement of NetShow technologies.The Windows Media SDK...
streaming video showing Haliaeetus pelagicus]. Retrieved 2006-DEC-01. - Photos of Steller's Sea Eagle by renowned nature photographer Klaus Nigge
- Natural Research Ltd.: Steller's Sea Eagle Studies. Retrieved 2006-DEC-01.