Estimating little auk (Alle alle) breeding density and chick-feeding rate using video surveillance

Abstract

High Arctic ecosystems are under change and need to be monitored. We studied little auks (Alle alle), the most abundant seabird in the North Atlantic, in their main breeding area in the North Water Polynya region of High-Arctic north-west Greenland. We developed a method for estimating breeding density and chick-feeding rate based on video surveillance. As the nests of little auks are secluded between rocks and cannot be directly observed, the method rests on detailed recording of feeding events, when parent birds arrive from the sea with filled gular pouches and disappear into the scree to feed their chicks, supplemented with recording of fledging and pre-fledging behaviour of chicks outside the nesting holes. We installed video cameras in two study plots during the late chick-rearing and fledging periods 2 – 11 August 2012 and 5 – 12 August 2013, and the method proved useful for estimating the density of active nests immediately prior to fledging (which corresponds roughly to productivity of fledglings/m2). The densities of active nests for the two plots in 2012 and 2013 ranged between 1.06 and 1.63 nests/m2, and an average of 9.1 feeds/chick/day (n = 8 pairs, 3 × 24 h, 219 feedings) was recorded for this late stage of the chick-rearing period. Our video surveillance method has advantages over the mark–resight methods and other techniques used to monitor little auk colonies.