Falklands Conservation

Southern Giant Petrel Census For The Falkland Islands
A Report by Nic Huin and Tim Reid

The first census of the Southern Giant-petrel in the Falkland Islands has just been completed. It is now known that nearly 20,000 pairs breed here, a much greater number that the previous estimation of between 5,000-10,000. The world population of around 31,000 must now be re-evaluated and the significance of the Falkland Islands, holding a possible 45% of global numbers, be re-assessed and its importance as a stronghold for this species recognised.

Southern Giant Petrel

The census revealed a total of 19,810 breeding pairs of Southern Giant Petrels. The distribution and size of the breeding colonies can be seen in the accompanying map. This shows two main concentrations: one on the west of West Falkland with 26% of the population, and the second, and most important, to the south of Falkland Sound with 72% of the population.

All known and suspected colonies of breeding Giant-petrels were surveyed between November 2004 and March 2005 - a total of 47 sites (See Map below). At four sites, where they were known to have bred in the past, no breeding adult birds were found this season. A further seven sites had no chicks, but may originally have had breeding adults. The remaining 38 sites held between one and 10,986 breeding pairs of Southern Giant Petrels. 

In November and December all nests with breeding adults incubating were counted at each individual colony. In January, February and March all chicks and their present parents were counted. 

Southern Giant Petrel Chick

Each colony was either surveyed by land, where direct counts were made or by air, where aerial photographs were taken and breeding pairs were subsequently counted. Thirteen colonies were counted both during incubation and chick-rearing periods. These were used to estimate an average breeding success. This data was then used to estimate the original number of breeding pairs in colonies where only chicks were counted in the second half of the season. Variations in the number of birds counted and in breeding success were used to give an estimate of the error inherent to such a census.

Further work remains to be done. A comprehensive report of the census will now be produced with a detailed account of methods, results, background information and conservation issues. It will put these census results into context both locally and in terms of the world wide population. A framework for future monitoring of the Southern Giant Petrel in the Falklands will be developed, including how best to monitor trends in the size of the Islands’ population, describing any significant lack of knowledge about its ecology, threats it may be facing, and how best to remedy them.

This census has been undertaken as part of a two year Albatross and Petrel Programme supported by the UK Overseas Territories Environment Programme (Foreign & Commonwealth Office) and the Falkland Islands Government.

April 2005.