A census of the black-browed albatross Diomedea melanophrys population on Steeple Jason Island, Falkland Islands

The world's largest colony of the black-browed albatross Diomedea melanophrys on Steeple Jason Island, Falkland Islands was systematically censused for the first time in December 1987. Colony area was estimated as 31·8 ha from high-altitude aerial photographs. Densities of both occupied and empty nests were estimated from counts in 31 quadrats covering 2·2% of the total colont area. Combining the colony area and nest density estimates indicated a total of between 196 600 and 232 700 nests, of which between 153 200 and 178 400 were occupied by breeding pairs over the hatching period. These results confirm the importance of this colony, and of the Falklands as a whole, to the world population of this species and provide a baseline against which to assess future population changes. Population monitoring is now essential as the foraging ecology of the albatrosses has been affected by the growth of commercial fisheries in Falkland's waters over the past decade.