Estimating colony area and population size of little auks Alle alle at Northumberland Island using aerial images

This paper presents a technique to estimate little auk population size from the area of the colonies measured by the use of video recordings and aerial photographs. To transform colony area into population size, breeding densities obtained from the literature were used. The study area, Northumberland Island, Thule District, Northwest Greenland, revealed between 6 and 12 million km2 inhabited colony area, which was classified into three categories for colony identification. The lower figure of this estimate is equivalent to a little auk population of 4.6 million pairs. An extrapolation to the rest of the Thule District should be treated with care but would amount to at least 33 million pairs. There is no doubt that the methods used would benefit from more fine-scale ground-truth surveys in the Thule District.