Night surveys and smell, a mixed method to detect colonies of storm petrel Hydrobates pelagicus

Abstract

Storm-petrels usually breed in sites difficult to access, making it hard to estimate the number of individuals in a colony or even the presence of a colony. After several years of study in the main colony and diurnal surveys to other caves of the island, we planned an extensive night survey for identifying previously unknown colonies. In the breeding season of 2011 we found 5 new colonies of storm petrels (Hydrobates pelagicus) at Marettimo island, increasing the estimation of the population on this island to approximately 3000 breeding pairs. We propose the use of mixed methods to locate new colonies, as they can be found by the characteristic smell of storm petrels, but under windy conditions it would be difficult. It is therefore very important to use night surveys to observe night activity by the individuals.