Evaluation of aerial surveys of ptarmigan Lagopus species

Abstract

1. We evaluated the reliability of aerial surveys to monitor trends in breeding population density of ptarmigan Lagopus spp. in south-western Yukon, Canada. 2. Aerial surveys provided repeatable indices of density. 3. Aerial indices of density were positively and linearly related to density between areas within the same year. 4. However, aerial indices of density were not positively related to density between years because the aerial index was lower in 1996 than in 1995, while in fact the density of ptarmigan increased. This could be explained by a reduction in the flushing response of ptarmigan in 1996. 5. We caution wildlife managers against a possible inter-year variation in the number of animals that can be seen from the air when conducting aerial surveys.