Diomedea exulans
Diomedea exulans
The snowy albatross or white-winged albatross, goonie (Diomedea exulans, Linnaeus 1758) is a bird belonging to the Diomedeidae family.
Systematic –
From a systematic point of view it appears to:
Eukaryota domain,
Kingdom Animalia,
Subkingdom Eumetazoa,
Superphylum Deuterostomia,
Phylum Chordata,
Superclass Tetrapoda,
Aves class,
Subclass Neornithes,
Superorder Neognathae,
Order Procellariiformes,
Family Diomedeidae,
Genus Diomedea,
Species D. exulans.
The following subspecies are recognized within this species:
– Diomedea exulans subsp. exulans Linnaeus, 1758;
– Diomedea exulans subsp. gibsoni C.J.R.Robertson & Warham, 1992.
Geographic Distribution and Habitat –
Diomedea exulans is a pelagic species that lives mainly in the sea. This bird takes advantage of marine currents and is capable of traveling more than 500 km in a single day. For nesting it chooses the Crozet Islands, Prince Edward Islands, South Georgia and the South Sandwich Islands, Kerguelen Islands and Macquarie Island.
These birds spend much of their lives in flight, landing only to breed and feed. Distances traveled each year are difficult to measure, but one bird was recorded traveling 6,000 km in twelve days.
Description –
Diomedea exulans has the longest wingspan of any living bird, typically ranging from 2.51 to 3.66 m. The longest-winged specimens verified measured approximately 3.7 m. Even larger examples have been claimed, with two giants measuring 4.22 m and 5.3 m, but these reports remain unverified. Thanks to its wingspan, it is able to remain in the air without flapping its wings for several consecutive hours (traveling 22 m for each meter of fall).
Body length ranges from approximately 107 to 135 cm with females being slightly smaller than males.
Adults can weigh 5.9 to 12.7 kg, although most weigh 6.35 to 11.91 kg.
The plumage varies with age, with juveniles starting out with a chocolate brown plumage. As they age they become whiter.
Adults have white bodies with black and white wings. Males have whiter wings than females with only the tips and trailing edges of the wings black.
This species is the whitest of the albatross species complex, the other species have much more brown and black on the wings and body of the breeding adults, closely resembling the immature D. exulans.
The beak is large and pink, as are the feet.
They also have a salt gland that sits above the nasal passage and helps desalinate their bodies, due to the high amount of ocean water they absorb. They expel a high-salt solution from their nose, which is a likely cause of the pink-yellow spot seen on the necks of some animals.
They live on average for 30 years.
Biology –
Diomedea exulans is a monogamous species that mates for life and reproduces every two years. During the breeding season they occupy colonies scattered across groups of isolated islands in the Southern Ocean. They lay a white egg, with some spots, about 10 cm long.
The deposition takes place between December 10th and January 5th. The nests have the shape of a large basin built with grassy vegetation and earthy peat, 1 meter wide at the base and half a meter at the apex.
Incubation lasts about 11 weeks and both parents are involved.
The 11-week incubation period is among the longest of any bird.
During the early stages of the chick’s development, the parents take turns sitting on the nest while the other searches for food. Thereafter, both adults forage for food and visit the chick at irregular intervals.
Adolescents return to the colony within six years; however they will not start reproducing until they are 11-15 years old.
After hatching the little one becomes self-sufficient in nine months.
The survival of the hatchlings is approximately 31.5%.
Ecological Role –
The Diomedea exulans is a bird that rarely stops on the ground, limiting its stops exclusively to nesting. It feeds on squid, small fish and waste thrown into the sea by ships, eating to the point of no longer being able to fly and being forced to rest in the water. For these reasons, according to maritime beliefs, this bird went around in a circle observing the water without ever stopping, sleeping in flight, ignoring adverse weather conditions. Although the large wings favor graceful flight and help it make the most of sea currents, they hinder it in taking off from the sea and landing, forcing it to take long run-ups.
The IUCN lists the snowy albatross as vulnerable. Adult mortality has ranged from 5% to 7.8% per year as of 2003. It has a range of 64,700,000 km2, although its breeding range is only 1,900 km2.
In 2007, there were approximately 25,500 adult birds, divided into 1,553 pairs on South Georgia Island, 1,850 pairs on Prince Edward Island, 1,600 on Marion Island, 2,000 on Crozet Islands, 1,100 on Kerguelen Islands, and 12 on Macquarie Island for a total of 8,114 nesting pairs. South Georgia’s population is declining by 1.8 percent per year. Bird levels in Prince Edward and Crozet Islands appear to be stabilising, although there may be some population contraction more recently.
The biggest threat to their survival is longline fishing; however, pollution, especially plastic and fishing hooks, is also having a negative impact. CCAMLR has introduced measures to reduce albatross bycatch by 99% around South Georgia and other regional fisheries commissions are taking similar measures to reduce casualties. Prince Edward Islands is a nature reserve and the Macquarie Islands are a World Heritage Site. Finally, a large part of the Crozet Islands and the Kerguelen Islands are a nature reserve.
Guido Bissanti
Sources
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– C.Battisti, D. Taffon, F. Giucca, 2008. Atlas of nesting birds, Gangemi Editore, Rome.
– L. Svensson, K.Mullarney, D. Zetterstrom, 1999. Guide to the Birds of Europe, North Africa and the Near East, Harper Collins Publisher, United Kingdom.
Photo source:
– https://inaturalist-open-data.s3.amazonaws.com/photos/292880014/original.jpeg