African Fish-eagle

The African Fish-eagle (Haliaeetus vocifer[1]) or - to distinguish it from the Ichthyophaga true fish eagles, African Sea-eagle - is a large species of eagle and a bird of prey.

Its closest relative appears to be the critically endangered Madagascar Fish-eagle. As in all sea-eagle species pairs, thie one consists of a white-headed species (the African Fish-eagle) and a tan-headed one. These are an ancient lineage of sea-eagles, and as such have dark talons, beaks, and eyes (Wink et al. 1996). Both species have at least partially white tails even as juveniles.

African Fish-eagles are large birds, and the females are often larger than the males. Males usually have a wingspan of about 6 feet, while females have wingspans upwards of 8 feet. They are very distinctive in appearance with a mostly brown body and large, powerful, black wings. The head, breast, and tail of African Fish-eagles are snow white and the hook-shaped beak is mostly yellow with a black tip.
An African Fish Eagle in the Okavango Delta

This species is still quite common near freshwater lakes, reservoirs, or rivers, although they can sometimes be found near the coast at the mouths of rivers or lagoons. As their name implies, African Fish-eagles are indigenous to Africa, ranging over most of continental Africa south of the southern-most edge of the Sahara Desert.

Breeding season for African Fish-eagles is during the dry season, when water levels are low. African Fish-eagles are believed to mate for life, and pairs will often maintain two or more nests, which they will frequently re-use. Because nests are re-used and built upon over the years the nests can grow to be quite large, some reaching six feet across and 4 feet deep. The nests are placed in a large tree and built mostly of sticks and other pieces of wood. The female lays 1 to 3 eggs, which are primarily white with a few reddish speckles. Incubation is mostly done by the female, but the male will incubate when the female leaves to hunt. Incubation lasts for 42 to 45 days before the chicks hatch. The eggs will often hatch a few days apart, and the eldest chick will usually kill any younger chicks. Fledging lasts for 70 to 75 days, and after about 8 weeks the chick is capable of feeding itself and will usually begin to venture outside of the nest 2 weeks later.

African Fish-eagles mainly feed on fish, which, upon spying it from a perch in a tree, it will swoop down upon and snatch from the water with its large clawed talons and fly back to its perch to eat. Should the African Fish-eagles catch a fish over 4 pounds it will be too heavy to allow it to get lift, so it will instead drag the fish across the surface of the water until it reaches the shore. Should the African Fish-eagles catch an especially heavy fish that is too heavy to even allow the eagle to sustain flight it will drop into the water and paddle to the nearest shore with its wings. African Fish-eagles will also feed on waterfowl, small turtles, baby crocodiles, and carrion.

African Fish-eagle

The African Fish-eagle (Haliaeetus vocifer[1]) or - to distinguish it from the Ichthyophaga true fish eagles, African Sea-eagle - is a large species of eagle and a bird of prey.

Its closest relative appears to be the critically endangered Madagascar Fish-eagle. As in all sea-eagle species pairs, thie one consists of a white-headed species (the African Fish-eagle) and a tan-headed one. These are an ancient lineage of sea-eagles, and as such have dark talons, beaks, and eyes (Wink et al. 1996). Both species have at least partially white tails even as juveniles.

African Fish-eagles are large birds, and the females are often larger than the males. Males usually have a wingspan of about 6 feet, while females have wingspans upwards of 8 feet. They are very distinctive in appearance with a mostly brown body and large, powerful, black wings. The head, breast, and tail of African Fish-eagles are snow white and the hook-shaped beak is mostly yellow with a black tip.
An African Fish Eagle in the Okavango Delta

This species is still quite common near freshwater lakes, reservoirs, or rivers, although they can sometimes be found near the coast at the mouths of rivers or lagoons. As their name implies, African Fish-eagles are indigenous to Africa, ranging over most of continental Africa south of the southern-most edge of the Sahara Desert.

Breeding season for African Fish-eagles is during the dry season, when water levels are low. African Fish-eagles are believed to mate for life, and pairs will often maintain two or more nests, which they will frequently re-use. Because nests are re-used and built upon over the years the nests can grow to be quite large, some reaching six feet across and 4 feet deep. The nests are placed in a large tree and built mostly of sticks and other pieces of wood. The female lays 1 to 3 eggs, which are primarily white with a few reddish speckles. Incubation is mostly done by the female, but the male will incubate when the female leaves to hunt. Incubation lasts for 42 to 45 days before the chicks hatch. The eggs will often hatch a few days apart, and the eldest chick will usually kill any younger chicks. Fledging lasts for 70 to 75 days, and after about 8 weeks the chick is capable of feeding itself and will usually begin to venture outside of the nest 2 weeks later.

African Fish-eagles mainly feed on fish, which, upon spying it from a perch in a tree, it will swoop down upon and snatch from the water with its large clawed talons and fly back to its perch to eat. Should the African Fish-eagles catch a fish over 4 pounds it will be too heavy to allow it to get lift, so it will instead drag the fish across the surface of the water until it reaches the shore. Should the African Fish-eagles catch an especially heavy fish that is too heavy to even allow the eagle to sustain flight it will drop into the water and paddle to the nearest shore with its wings. African Fish-eagles will also feed on waterfowl, small turtles, baby crocodiles, and carrion.

Steller's Sea Eagle

The Steller's Sea Eagle, Haliaeetus pelagicus is a large bird of prey in the family Accipitridae which also includes many other diurnal raptors such as kites, buzzards and harriers. This is, on average, the heaviest eagle in the world, as it averages about 6.8 kg (15 lb), but may lag behind the Harpy Eagle and the Philippine Eagle in other measurements.

This bird breeds on the Kamchatka peninsula, 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 further south, in the southern Kuril islands 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.

Description, systematics and status

Stellers' Sea-eagle is the biggest bird in the Genus Haliaeetus and is one of the largest raptors overall. The typical size range is 86.5-105 cm (34-41 inches) long and the wingspan is 203-241 cm (6.8-8 feet). On average, females weigh from 6.8 to 9 kg (15 to 20 lb), while males are considerably lighter with a weight range from 4.9 to 6 kg (10.8 to 13.2 lb). An unverified record exists of a huge female, gorged on salmon, having weighed 12.7 kg (28 lb).

This species is classified as Vulnerable. The main threats to its survival are habitat alteration, industrial pollution and over-fishing. The current population is estimated at 5,000 and decreasing.

Two subspecies have been named: the nominate pelagicus, and the Korean Sea-eagle, Haliaeetus pelagicus niger[2]. The latter name was given to the Korean population which was apparently resident all year and lacked white feathers except for the tail. Its validity is disputed; it may have been a morph and not a genetically distinct population. In any case, the Korean population of this species is extinct since the 1950s due to habitat loss and hunting.

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 Eagles, and biogeography.(Wink et al., 1996)

The large size (see also Bergmann's Rule) suggests that it is a glacial relic, meaning that it evolved in a narrow subarctic zone of the northeasternmost Asian coasts, which shifted its latitude according to ice age cycles, and never occurred anywhere else. It is unique among all sea eagles in having a yellow bill even in juvenile birds, and possessing 14, not 12, rectrices.

Food

The Steller's Sea-eagle mainly feeds on fish, especially salmon and trout. Besides fish, it also preys on water-dwelling birds, mammals and carrion. This eagle may prey on young seals, but seals are generally more likely to be eaten as carrion.

Reproduction

This eagle builds several aeries (height, 150 cm; diameter up to 250 cm) high up on trees and rock. It is possible that the eagles change occasionally between these nests. After courtship, which usually occurs between February and March, the animals lay their first white-green eggs 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. At an age of around ten weeks, the young birds learn to fly, while they reach sexual maturity at around four to five years. Only at the age from eight to ten years a Steller's Sea-eagle is wearing full adult plumage.