The maritime Antarctic South Sandwich Islands (Islas Sandwich del Sur)* consist of an arc about 400 km in length of 11 little-visited islands in the South Atlantic sector of the Southern Ocean south of the Antarctic Polar Front. The islands are usually ice-bound in winter.
Known especially for its very large penguin populations the island chain has been designated an Important Bird Area.
Over the period 1 January – 5 February 2011 biologists landed from rubber inflatable boats from the motor yacht Golden Fleece on 10 of the 11 main islands in the group with the aim of surveying the populations of penguins of several species (including by use of satellite imagery) and of other breeding birds on the islands (click here).
Although observed throughout the islands in 2011, breeding Southern Giant Petrels Macronectes giganteus (the only ACAP-listed species) were recorded on only two islands: Zavodovski (at 25 km² the most northerly in the group and mainly free of ice) and Candlemas (Candelaria, partially ice-covered at 14 km²). Both islands support intermittently active volcanoes with their highest peaks at 550 m. Breeding sites could thus be at risk to future eruptions. Vegetation is restricted mainly to mosses and lichens and to a single vascular species (Antarctic Hair Grass Deschampsia antarctica) on Candlemas.
Both islands have always been uninhabited, although Zavodovski currently supports an automatic weather station operated by South Africa.
Zavodovski from the Golden Fleece anchored off Fume Point. A large Chinstrap Penguin Pygoscelis antarctica colony and the volcano cone that dominate the island are visible
Small numbers of giant petrels were found breeding on the flat ash plains at the northern end of the island near Reek Point on 12 January 2011, making a total of 64 nests.
Small groups of Southern Giant Petrels breed on the ash plain
in the north of Zavodovski
Two Southern Giant Petrel colonies were surveyed on 17 and 19 January 2011 with a total of 1818 occupied nests, divided roughly between 1682 nests encountered in scattered groups on the northern Breakbones Plateau and 136 nests in the south-west of the island.
Three views of Candlemas Island from the sea
The most recent previous counts of breeding Southern Giant Petrels in the South Sandwich Islands (Islas Sandwich del Sur)* were of 1516 pairs on Candlemas and 25 pairs on Zavodovski in January 1997. The 2011 total of 1882 is higher than that of the 1996/1997 breeding season but should not be taken as necessarily reflecting a population change. However, it should be noted that at the time of the survey in mid-January many giant petrels were brooding small chicks. Although the surveys conducted were as thorough as possible in the limited time available ashore the lateness of the season means that pairs that failed during incubation were not recorded.
Southern Giant Petrels were found breeding within lava boulder rubble on Candelmas
A Southern Giant Petrel broods its downy chick on Candelmas Island
Southern Giant Petrels were seen ashore on Bellingshausen Island in what looked like suitable habitat but no evidence of breeding was found. White-morph Southern Giant Petrels were seen at several sites, with a small percentage (3-5%) of breeding birds at Candlemas being of this morph.
Northern Giant Petrels M. halli were recorded ashore and in coastal waters of all the islands, frequently observed scavenging and preying upon penguins. The largest number recorded was 25 birds at Irving Point on Visokoi Island. No breeding was observed within the island group, nor has it been previously.
Click here to read more about the 2011 survey.
All photographs by Andy Black.
Baker, P.E., Holdgate, M.W., Longton, R.E., Tilbrook, P.J., Tomblin, J.F., Vaughan, R.W. & Wynne- Edwards, C.J.C. 1964. A survey of the South Sandwich Islands. Nature 203: 691-693.
Convey, P., Lewis Smith, R.I., Hodgson, D.A. & Peat, H.J. 2000. The flora of the South Sandwich Islands, with particular reference to the influence of geothermal heating. Journal of Biogeography 27: 1279-1295.
Convey, P., Morton, A. & Poncet, J. 1999. Survey of marine birds and mammals of the South Sandwich Islands. Polar Record 35: 107-194.
Holdgate, M.W. 1963. Observations in the South Sandwich Islands, 1962. Polar Record 11: 394-405.
Holdgate. M.W. & Baker, P.E. 1979. The South Sandwich Islands, I. General description. British Antarctic Survey Report No. 91.
Lynch, H.J., White, R.W., Black, A.D. & Naveen, R. 2012. Detection, differentiation and abundance estimation of penguin species by high-resolution satellite imagery. Polar Biology 35: 963-968.
Lynch, H.J., White, R.W., Black, A.D. & Naveen, R. In preparation. A biological survey of the South Sandwich Islands, 1 January – 5 February 2011.
Patterson, D.L., Woehler, E.J., Croxall, J.P., Cooper, J., Poncet, S., Peter, H.-U., Hunter, S. & Fraser, W.R. 2008. Breeding distribution and population status of the Northern Giant Petrel Macronectes halli and Southern Giant Petrel M. giganteus. Marine Ornithology 36: 115-124.
Click here for the paper's separate appendices with historical count data.
Poncet, S. 2006. South Georgia and the South Sandwich Islands. In: Sanders, S.M. (Ed.). Important Bird Areas in the United Kingdom Overseas Territories. Sandy: Royal Society for the Protection of Birds. pp. 211-226.
Shirihai, H. 2007. A Complete Guide to Antarctic Wildlife. The Birds and Marine Mammals of the Antarctic Continent and the Southern Ocean. London: A & C Black. pp. 449-451.
Andy Black, South Georgia (Islas Georgias del Sur)* & John Cooper, ACAP Information Officer, 26 November 2013
*A dispute exists between the Governments of Argentina and the United Kingdom of Great Britain and Northern Ireland concerning sovereignty over the Falkland Islands (Islas Malvinas), South Georgia and the South Sandwich Islands (Islas Georgias del Sur y Islas Sandwich del Sur) and the surrounding maritime areas.