Albatrosses

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Albatrosses

Set: Part No: ST011556
As a group, albatrosses are the most endangered family of birds in the world with 15 of the 22 species listed by IUCN as Vulnerable, Endangered or Critically Endangered. South Georgia supports internationally important populations of four species of albatross, including the world’s largest populations of grey-headed and, probably, light-mantled albatross, the second largest population of wandering albatross and the third largest population of black-browed albatross.

On South Georgia, the majority of albatross breeding sites are found on offshore islands at the northern and southern extremes of mainland South Georgia (and Annenkov Island); the exception being the light-mantled albatross, which are scattered across the entire Island. Bird Island, off the northern tip of South Georgia, is the most significant breeding site for albatrosses in the archipelago and home to one of the two British Antarctic Survey bases on the islands.

Since the 1970s, annual counts of all wandering albatross nests and selected study colonies of black-browed and grey-headed albatrosses have shown a steady decline in the populations of all these birds. Island wide censuses in the 1980s were repeated in 2003/04 and confirmed the declining trend throughout the Islands. It is believed that the major threats to these species are encountered at-sea, many birds are known to be killed in longline and trawl fisheries throughout the southern hemisphere. Although there are fisheries within the SGSSI Marine Protected Area, strict mitigation measures are used to reduce seabird mortality to minimal levels. However, albatrosses travel vast distances to feed or overwinter in other regions, where they are exposed to numerous fisheries that are not so strictly regulated.  

Black-browed albatross Thalassarche melanophris

On South Georgia, black-browed albatross breed colonially on steep tussac covered slopes, sometimes mixed with grey-headed albatross. The average age of first time breeders is 10 years of age for this annually breeding species. Adults return to colonies in September and chicks fledge in April or May. Outside the breeding period, these birds depart from South Georgia to forage over continental shelf waters off the west coast of southern Africa. It is here that they are exposed to mortality in a number of trawl and longline fisheries. The last island-wide census of the South Georgia breeding population in 2003/04 recorded 74,296 pairs, which represented about 12.4% of the world population.

Grey-headed albatross Thalassarche chrysostoma

Although often found breeding along with black-browed albatrosses, grey-headed albatross only attempt to breed every other year. On average, these birds do not breed for the first time until they are 12 years old. Breeding birds return to colonies in September and chicks fledge in April or May. Outside the breeding season, most of these birds depart from South Georgia waters and spread widely throughout the Southern Ocean, and may make several complete global circum-navigations between breeding attempts. The last Island-wide census (in 2002/03) recorded 47,674 breeding pairs, which represents approximately half of this Endangered species’ global population.

The best place for visitors to South Georgia to see grey-headed and black-browed albatross is Elsehul, where several colonies can be seen on the steep sides of the bay. 

Light-mantled albatross Phoebetria palpebrata

Unlike the other species of albatross breeding on South Georgia, light-mantled albatross are wide-spread and can be found in low numbers around the entire coastline. The dispersed nature of nest sites mean that an island-wide census would be extremely difficult and has not been attempted to-date. However, the South Georgia population is estimated to be between 5-7,500 pairs, equivalent to about 25% of the world population, representing the world’s largest breeding population. It is not possible to assess the population trend of this species.

Light-mantled albatross are biennial breeders that return to breed in September and chicks fledge in late May or June. During courtship, pairs of engage in synchronised flight, which is very characteristic of this species.

Light-mantled albatross are regarded as the most southerly distributed of all the albatross species, often foraging near the edge of the Antarctic pack-ice.    

Wandering albatross Diomedea exulans

South Georgia is home to approximately 25% of the world’s wandering albatross population. They breed at 30 sites on South Georgia, including Prion Island where visitors have the opportunity to see these birds on the nest. However, the majority (61%) are found on Bird Island off the northern tip of the mainland. Annual counts of the nests of this biennially breeding species have identified a steady decline in numbers, between 1984 and 2004 the population fell by 30%.

Wandering albatross are one of the largest flying birds in the world, with a wingspan of up to 3.5 m and weight of 12 kg. To raise a chick to this size takes nearly a year with eggs laid in December or January producing fledglings in the following December. During the breeding period, adults may fly over 4,000 km from the nest site in search of food, which is mostly squid.  

As part of their commitment to the international Agreement on the Conservation of Albatross and Petrels (ACAP) the Government of South Georgia & South Sandwich Islands will be undertaking surveys of black-browed, grey-headed and wandering albatross during the 2014/15 austral summer.  The black-browed and grey-headed albatross survey will take place in November 2014 using the Fisheries Patrol Vessel Pharos SG and will involve photographing key nesting sites.  The wandering albatross survey will take place in January 2015 and will be supported by the Hans Hanssen and will visit all the nesting sites of this species.

Text by Andy Black.

Technical Details
Designer                           Nick Shewring
Printer                               BDT International
Process                             Lithography
Perforation                        14 per 2cms
Stamp size                         51.46 x 30.00mm
Sheet Layout                     10
Release date                     30 January, 2015
Production Co-ordination   Creative Direction (Worldwide) Ltd