By Danielle Nelson
Geographic Range
Steller's sea eagles are native to eastern Russia, specifically, the Sea of Okhotsk and the Kamchatka Peninsula. They are frequent winter migrants south to the Japanese Islands of Kuril and Hokkaido and have been seen as far south as eastern China and Korea. Vagrant individuals have also been spotted in Taiwan and the United States. ("BirdLife International Species factsheet: Haliaeetus pelagicus", 2007; "Species Synopsis Stellar Sea Eagle", 1999)
Biogeographic Regions:
palearctic 
(native ).
Habitat
(328 ft)
Steller's sea eagles breed along sea coasts or near large rivers with mature trees. Sightings very far inland are rare, as they prefer sea coasts that are dotted with estuaries and river mouths. They nest on large, rocky outcroppings or at the tops of large trees. Steller's sea eagles are generally found at elevations ranging from sea level to approximately 100 m. ("BirdLife International Species factsheet: Haliaeetus pelagicus", 2007; "Species Synopsis Stellar Sea Eagle", 1999)
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. (Collar, 2001)
These animals are found in the following types of habitat:
temperate ; terrestrial ; saltwater or marine ; freshwater .
Aquatic Biomes:
rivers and streams; coastal .
Physical Description
(33.46 to 37.01 in)
Steller's sea eagles are large eagles with dark brown to black feathers on the majority of the body and white on the shoulders, thighs, and crown. They have wedged-shaped, white tails, very large yellow beaks, and sharp, yellow talons. Average mass is 6 kilograms in males and 9 kilograms in females. Body length of both males and females ranges between 85 and 94 centimeters with average wingspans of females around 136 centimeters and males around 118 centimeters. ("BirdLife International Species factsheet: Haliaeetus pelagicus", 2007; "Species Synopsis Stellar Sea Eagle", 1999; Brown and Amadon, 1989)
Some key physical features:
endothermic ; homoiothermic; bilateral symmetry .
Sexual dimorphism: female larger.
Reproduction
Steller's sea eagles breed once yearly.
Breeding occurs from February through August.
Steller's sea eagles are monogamous, they are often seen in breeding pairs throughout the breeding season, usually lasting from February through August. Both males and females secure their own breeding territories early in the season and nest building occurs in February or March. Displaying begins in March and consists of soaring high above the breeding area while calling. ("BirdLife International Species factsheet: Haliaeetus pelagicus", 2007; "Species Synopsis Stellar Sea Eagle", 1999)
Mating systems:
monogamous .
Both male and female Steller's sea eagles reach sexual maturity by six or seven years. Breeding occurs seasonally between February and August, beginning with nest building in February and March. Typically, a pair will maintain two to four nests in one breeding territory and use alternate nests from year to year. Nests are most often built on rocky cliffs or in large trees out of thick branches and can reach a size of two meters across and two to four meters thick. The average clutch size is 2 but ranges from 1 to 3. The egg-laying period normally lasts from April through May, and the typical incubation period is 38 days. Eggs hatch between May and June, with fledging taking around 70 days. Chicks leave nests by August or September. ("BirdLife International Species factsheet: Haliaeetus pelagicus", 2007; "Species Synopsis Stellar Sea Eagle", 1999; Collar, 2001)
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous .
At this time, little is known about the parental investment of Steller's sea eagles. Both parents contribute to raising offspring to independence. ("BirdLife International Species factsheet: Haliaeetus pelagicus", 2007; "Species Synopsis Stellar Sea Eagle", 1999)
Parental investment:
altricial ; pre-fertilization (provisioning, protecting: female); pre-hatching/birth (provisioning: female, protecting: male, female); pre-weaning/fledging (provisioning: male, female, protecting: male, female); pre-independence (provisioning: male, female, protecting: male, female).
Lifespan/Longevity
Little is known about the lifespan of Steller's sea eagles, but it is thought to be similar to that of their close relatives, white-tailed sea eagles (Haliaeetus albicilla), which live 20 to 25 years in the wild. ("BirdLife International Species factsheet: Haliaeetus pelagicus", 2007; "Species Synopsis Stellar Sea Eagle", 1999)
Behavior
Steller's sea eagles are solitary birds, congregating with others only to breed. However, large numbers can be seen congregating on particularly productive salmon rivers due to an abundant food supply. Steller's sea eagles are commonly seen perching on cliffs above the sea or in large trees. They are active during the day and migrate to warmer areas in the winter. ("BirdLife International Species factsheet: Haliaeetus pelagicus", 2007; "Species Synopsis Stellar Sea Eagle", 1999)
Home Range
Home range sizes of Steller's sea eagles are not known, but productive nests have been reported to be as close as within 100 meters. (Collar, 2001)
Communication and Perception
Steller's sea eagles communicate mainly through various vocalizations. A deep, barking cry is commonly heard. During mating displays a loud, gull-like call is used. ("BirdLife International Species factsheet: Haliaeetus pelagicus", 2007; "Species Synopsis Stellar Sea Eagle", 1999)
Communicates with:
acoustic .
Food Habits
The main prey of Steller's sea eagles are salmon, taken either dead or alive. When salmon is scarce or not available, other food resources are taken, ranging from invertebrates like crabs and mussels to gulls, small mammals, and carrion. Three types of hunting behaviors have been observed, hunting from a perch, hunting on the wing while circling 6 to 7 meters above the water, and hunting in shallow water. Kleptoparasitism has also been observed when feeding occurs in groups and food is abundant, adults benefit the most from this behavior. ("BirdLife International Species factsheet: Haliaeetus pelagicus", 2007; "Species Synopsis Stellar Sea Eagle", 1999; Brown and Amadon, 1989)
Animal Foods:
birds; mammals; fish; carrion ; mollusks; aquatic crustaceans.
Predation
There are no known predators of adult Steller's sea eagles. Eggs and hatchlings are commonly preyed on by arboreal mammals that gain access to nests, such as martens, and by crows. ("BirdLife International Species factsheet: Haliaeetus pelagicus", 2007; "Species Synopsis Stellar Sea Eagle", 1999)
Ecosystem Roles
Steller's sea eagles are important predators of salmon and other prey in their native ecosystems. ("BirdLife International Species factsheet: Haliaeetus pelagicus", 2007; "Species Synopsis Stellar Sea Eagle", 1999)
Economic Importance for Humans: Negative
Steller's sea eagles have been known to remove mammals from commercial traps set by humans during harsh winters, causing some harm to that industry. ("BirdLife International Species factsheet: Haliaeetus pelagicus", 2007; "Species Synopsis Stellar Sea Eagle", 1999)
Economic Importance for Humans: Positive
There are no described benefits of Steller's sea eagles to humans.
Conservation Status
IUCN Red List: [link]:
Not Evaluated.
US Migratory Bird Act: [link]:
Protected.
US Federal List: [link]:
No special status.
CITES: [link]:
Appendix II.
State of Michigan List: [link]:
No special status.
Steller's sea eagles have a limited population size of around 5,000 individuals. Populations are in steady decline. Potential causes of declining populations are habitat degradation due to an increase in industry and logging, overfishing of key prey items, and pollution.
Steller's sea eagles are listed as vulnerable on the IUCN Red List of Threatened Species because of their small and declining population sizes. Steller's sea eagles are legally protected in Russia, Japan, China, and South Korea with key habitat areas being established as nature reserves throughout Russia and Japan. They are also protected under Appendix II of the Convention on International Trade of Endangered Species.
For More Information
Find Haliaeetus pelagicus information at
Contributors
Tanya Dewey (editor), Animal Diversity Web, University of Michigan Museum of Zoology.
Danielle Nelson (author), Northern Michigan University. Dr. Alec R. Lindsay (editor, instructor).
