Nest boxes as a tool for the monitoring of vulnerable Yelkouan Shearwaters in the Maltese Islands

Abstract

Yelkouan Shearwaters nest in largely inaccessible crevices and caves making monitoring efforts time-consuming and prone to low sample sizes. Here we describe the first successful nesting of Yelkouan Shearwaters in artificial nests in the Maltese Islands. Nest boxes were made of marine plywood, with a nesting chamber separated from an entrance corridor, providing a relatively cheap conservation and monitoring tool. The design used is also different to other artificial nesting chambers used elsewhere for the species, providing several advantages. Out of two deployed in 2013 and 81 deployed in 2016–2018; 17 nest boxes have showed prospecting activity and of these seven have been occupied by breeding pairs as of the 2019 breeding period. The fact that 20% of boxes showed signs of activity within only three years of deployment is very encouraging and shows that Yelkouan Shearwaters will use this design for breeding purposes. It seems likely that occupation rates will continue to increase in following years. Apart from providing more data on suitable locations for deployment (not only locally but also at a regional level), occupied nest boxes can be an important additional conservation action as well as providing easy access to breeding phenology data when compared with natural nests.