A protocol for using drones to assist monitoring of large breeding bird colonies

Drones are rapidly becoming part of environmental monitoring and management applications. They provide an opportunity to improve a number of activities related to monitoring population dynamics of aggregations of wildlife. Bird surveys using drones have attracted particular attention, with a range of potential metrics able to be derived from high resolution drone imagery. Whilst a number of papers have shown that drone-based data can be used to effectively and accurately count and monitor features in bird colonies, the use of drone-derived data in real management and monitoring applications remains rare. This is in part due to a lack of clear guidelines as to the capability of drones and how to plan and successfully execute flights, but also due to a lack of information pertaining to specific target species and related contextual and environmental considerations. In this paper we outline a protocol for using drones to assist in the monitoring of colonies of breeding colonial waterbirds. We base the protocol on experience carrying out drone-based surveys of several colonies ranging in population from ~1000 to ~250,000 individuals. These are among the largest colonies ever surveyed via drone. We provide end-to-end guidelines, including detectability, flight planning and execution, on-ground data collection, image processing and target feature counting.