Birds of Prey: The Steller's Sea Eagle
While those of us in the western hemisphere may not be overly familiar with the Steller’s Sea Eagle, this beautiful member of the eagle family is certainly worth getting to know. When measured by average weight, the Steller’s Sea Eagle is the heaviest bird of prey in the world. Slightly smaller in dimensions than the Harpy Eagle of Central and South America and the Philippine Eagle, the Steller’s Sea Eagle lives in the coastal regions of northeastern Asia.
The sheer size of the Steller’s Sea Eagle is enough to make this raptor one of the most impressive birds in the world. With adult females reaching 15 to 20 pounds, and a wingspan of between six to eight feet, the Steller’s size strikes an impressive and imposing figure. As is typical of birds of prey, the male is much smaller than the female and will weigh from 11 to 13 pounds. Steller’s will range from about 33 inches in length up to as much as 41 inches for the largest adults.
Steller’s Sea Eagles are generally black to dark brown over most of their body. They have very distinctive white feathers on their shoulders, legs, tail and crown. Their eyes, feet, and very large bill, are all a very bright yellow in color and they have the largest skull of any eagle anywhere in the world. Their full adult coloring is not reached until they are approximately five years old, which is when they reach their sexual maturity. Newborn eaglets are initially a very silky white, which quickly turns to a brownish-grey color within a few weeks.
Habitat and Range
The Steller’s Sea Eagle is pretty much confined to northeast Asia in the area around the Kamchatka Peninsula of Russia and the Sea of Okhotsk. Steller's have been found as far south as Taiwan and in North America, but they are considered to be individuals that have wandered from their normal range.
Generally, Steller’s Sea Eagles can be found in one of two habitats: near large rivers and along the sea coast. They prefer areas with large trees for nesting and their nest can be up to five feet deep and eight feet in diameter. In addition to nesting in large trees they will also nest on rocky cliffs. The nests of the Steller’s Eagle are called aeries and a pair will usually return to the same site yearly.
- Orange: breeding only
- Green: resident all year
- Blue: winter only
- Grey: vagrant range
Some, but not all Steller’s will migrate and this seems to be dependent on food availability and sea ice conditions. In the Kamchatka area of Russia many of the eagles will overwinter in the river valleys and forest. Those eagles that do migrate will winter in the southern Kuril Islands and near Hokkaido in northern Japan where they are close to rivers and lakes. They will usually stay until late March to late April before heading back north.
Steller’s feed on a variety of food but fish is their most common meal. Trout and salmon seem to be their favorite prey. The annual salmon runs are a time for the Steller’s to feast as they compete with brown bears, golden eagles, and other raptors for their favorite meal.
Steller’s will spend a good portion of their day perched high up in a tree as they scan the area for food. With binocular like vision they can spot their prey from a distance before swooping in for the kill. Steller's are powerful enough to catch a fish on the fly and their large talons make for quite the weapon. On occasion they will also hunt small mammals, crabs, other birds, and they are also not opposed to scavenging and stealing food from other raptors.
Steller’s Sea Eagles will lay their eggs in mid-spring after a late winter courtship. They will usually lay between one to three eggs that are a greenish white in color. The eggs will incubate for 40 to 45 days during which time the female will rarely leave the nest. Generally only one chick will survive, but this is not always the case, and occasionally two and even three chicks will be raised successfully. The chicks are born with a white silky down that will quickly change to a brownish-grey color as they quickly grow. It normally takes about ten weeks for the eaglets to fledge and this usually takes place by August or September. It will take about five years for the Steller's Sea Eagle to reach their sexual maturity and full color.
- The Steller’s Sea Eagle is named after Georg Wilhelm Steller, a noted 18th-century explorer and zoologist.
- Steller’s are called O-washi in Japan where they are revered and honored.
- They are considered one of the largest of all eagles species along with the Philippine Eagle and the Harpy Eagle.
- A group of Steller’s Sea Eagles is referred to as a “constellation”.
- They are diurnal, meaning they hunt during the day.
- The Scientific name of the Steller’s Sea Eagle is Haliaeetus pelagicus.
- They are unique among all other sea eagles in that they have a bright yellow beak even in juvenile birds.
- Also referred to as the White-shouldered Eagle or the Pacific Eagle.
- Due to nests collapsing under their own weight and egg predation only about half to two-thirds of eggs successfully reach adulthood.
- Steller's Sea Eagles have no natural predators.
Because of their somewhat remote and limited location, not much is known about this eagle, especially during their early years. Current estimates place the population at about 5,000 and they are afforded complete legal protection in Russia. As is usually the case with raptors that are at the top of the food chain, their biggest threat comes from man. Habitat loss and river contamination are constantly putting pressure on this magnificent bird and their population is slowly decreasing despite the protection. Their current status is list as threatened and vulnerable.
Questions & Answers
© 2012 Bill De Giulio