Monitoring Colonies of Large Gulls Using UAVs: From Individuals to Breeding Pairs

Abstract

Measuring success or failure in the conservation of seabirds depends on reliable long-term monitoring. Traditionally, this monitoring has been based on line transects and total or point counts, all of which are sensitive to subjective interpretation. Such methods have proven to consistently record fewer individuals than intensive efforts, while requiring many hours of fieldwork and resulting in high disturbance. New technologies, such as drones, are potentially useful monitoring tools, as they can cover large areas in a short time, while providing high-resolution data about bird numbers and status. This study conducted two types of Uncrewed Aerial Vehicle (UAV) surveys in a big colony of multispecies breeding gulls. From a 25 m height, we photographed 30 circle plots where nests were also counted on the ground, showing that the number of occupied nests/breeding pairs could be estimated accurately by multiplying the number of counted individuals with a 0.7 conversion factor. A fixed-wing UAV was used to photograph the entire island to compare drone counts with counts conducted by traditional methods, were we counted a higher number of breeding pairs than the traditional count (1.7–2.2 times more individuals). It was concluded that UAVs provided improved estimates of colony size with much reduced monitoring effort.

Editorial for the Special Issue on Micro Air Vehicles

“…Shi et al [6] proposed an IAP configuration design with three sub-UAVs, investigated the geometric control of the integrated multi-UAV system, and developed an IAP prototype composed of software and hardware systems, offering a design and control foundation for building future multi-UAV IAPs. In addition, Corregidor-Castro et al [7] aimed to determine the advantages and disadvantages of the use of UAVs as monitoring tools to census colonies of two species of breeding seabirds, the Herring Gull (Larus argentatus) and the Lesser Black-backed Gull (Larus fuscus). Finally, Ji et al [8] provided theoretical references and technical support for the verification of the feasibility of the Trichogramma delivery system.…”