Amsterdam Albatross, Diomedea amsterdamensis
Amsterdam Albatross or Amsterdam Island Albatross, (Diomedea amsterdamensis), is a species of albatross belonging to the Diomedeidae family. It was first described in 1983 and was originally believed to be a subspecies of the Wandering Albatross. BirdLife International now recognizes it as a separate species, but it is still considered a subspecies to some.
The Amsterdam Albatross breeds only on Amsterdam Island, French Southern Territories in the southern Indian Ocean, at an elevation between 1,600 and 2,000 feet on Plateau des Tourbieres. It is unclear where this bird nests when it is not breeding; although there have been possible sightings in Australia and New Zealand.
This bird is listed as critically endangered by the International Union for Conservation of Nature (IUCN), with an occurrence range of 1.7 million square miles and a breeding range of only 2.7 square miles. Upon discovery, only 5 breeding pairs were found. But through successful conservation efforts, the population has increased to about 25 breeding pairs. The world population is estimated at 80 mature individuals and 130 birds in all.
The breeding habitat of the Amsterdam Albatross has undergone significant decline condition wise, due to the introduction of feral cats, cattle and longline fishing. And because there is only one breeding location, the birds are especially susceptible to disease. In an effort to continue conservation of this species, birds have been banded and frequent censuses are undertaken.
The adult is 42 to 48 inches long and weighs 11 to 18 pounds. It has a wingspan of 110 to 130 inches (9 – 11 feet). The adult has chocolate brown upper parts, and is white on its face mask, throat, lower breast, and belly. It has a broad brown breast band along with brown under tail coverts. It has a pink bill with a dark tip and dark cutting edges. The under wings are white except for the dark tip and the dark leading edge.
The Amsterdam Albatross produces a stomach oil made up of wax esters and triglycerides that is stored in the proventriculus (digestive system). This is used against predators as well as an energy rich food source for chicks and for the adults during their long flights.
The Amsterdam Albatross breeds in brown, rather than usual white, plumage. It breeds on a biennial basis in open marshy ground. Both parents incubate the egg, in weeklong turns. The chick hatches after about 80 days. It is brooded for a month, and will fledge in roughly 230 days. The parents both feed the chick about once every three days initially, and then at longer intervals as it nears fledging.
When fledging arrives, the chick weighs more than its parents, but will lose weight as the extra reserves are used to grow feathers. After fledging, the young bird will remain at sea for about 5 years before returning to the breeding colony. It will begin breeding a few years after its return.
Because of its rarity, the feeding ecology and at-sea distribution of the Amsterdam Albatross is not well understood; although, it is believed that they eat squid, crustaceans, and fish. Off-duty birds during the incubation stage of the breeding cycle cover large areas of the Indian Ocean, traveling up to 1,500 miles.
Image Caption: Amsterdam Albatross in flight. Credit: Vincent Legendre/Wikipedia (CC BY-SA 3.0)