The site comprises the whole of the South Sandwich Islands and associated islands, islets and stacks and is described in the 'General introduction'.
16 seabird taxa are known to breed. There are no resident landbird species. In addition to those given below, populations include 2 pairs of King Penguins, recorded breeding on Zavodovski Island in 1997, the most southerly known breeding location for this species. There are no accurate estimates for burrow-nesting species but it is likely that the combined populations for Antarctic Prions, Black-bellied Storm-Petrels and Wilson's Storm-petrels total a few tens of thousands of pairs. The only known population of Antarctic Prions occurs on ice-free Leskov Island. Black-bellied Storm-petrels have been recorded nesting on the stable ice-free areas of Candlemas, Saunders and Zavodovksi Islands, while Wilson's Storm-petrels are believed to nest on every island in the group. Imperial Cormorants nest in small colonies on coastal and offshore rock stacks, mainly around Montagu and Bristol Islands, with a total population of 300-400 pairs. Dominican Gulls and Antarctic Terns nest in small numbers, with possibly up to 100 pair for each. Nearly 1 million pairs of Chinstrap Penguins nest on Zavodovski Island, which also has the world's largest single colony estimated at nearly half a million pairs. This island is also the most northerly breeding location for Antarctic Fulmars, which nest on the steep cliffs of all islands except Bellingshausen. Two thirds of this species' population breed on Cook, Montagu and Visokoi Islands. Cape Petrels and Snow Petrels nest in scattered colonies on all islands, often in association with Antarctic Fulmars. Adelie Penguins nest in small colonies on Thule, Candlemas, Montagu, Cook, Bristol and Bellingshausen, with a large colony of around 50,000 pairs on Saunders Island. With the exception of 2 pairs of Adelie Penguins breeding on Annenkov Island at South Georgia, the population on Candlemas Island is the most northerly known for this species. Gentoo Penguins and Macaroni Penguins breed in small numbers amongst the Chinstrap Penguins on Thule, Visokoi, Candlemas and Saunders. The latter species also breeds on Zavodovski Island, where there are over 50,000 pairs, the largest population in the archipelago. Southern Giant Petrels breed on 2 islands only, with over 1500 pairs on Candlemas and possibly similar numbers on Zavodovski.
Non-bird biodiversity: Antarctic fur seals Arctocephalus gazella breed in small numbers on Zavodovski, Visokoi, Candlemas, Thule and Saunders Islands with nearly 1,800 pups recorded in 1997. Small numbers of elephant seals Mirounga leonina and Weddell seals Leptonychotes weddelli are present but there has been no confirmed breeding. Leopard seals Hydrurga leptonyx and crabeater seals Lobodon carcinophagus are regular visitors. No endemic plants have been recorded.
BirdLife International (2020) Important Bird Areas factsheet: South Sandwich Islands. Downloaded from http://www.birdlife.org on 30/10/2020.