Remotely piloted aircraft improve precision of capture–mark–resight population estimates of Australian fur seals

Abstract

Remotely piloted aircraft (RPA or drones) have become a powerful tool for use in spatial and temporal ecology. Major benefits for environmental management, including improved accuracy and precision for population monitoring of fauna, are being realized. We used Australian fur seals (Arctocephalus pusillus) as a model system to assess how counts and capture-mark-resight (CMR) estimates derived from RPA surveys compared with both traditionally used ground counts and CMR abundance estimates at two colonies in southeastern Australia. To manage the large volume of data, we implemented a citizen science portal SealSpotter to screen RPA imagery for animals of the target age classes. Capture-mark-resight estimates and direct counts using RPA imagery provided measurable improvement in monitoring precision when compared with traditional techniques. A key methodological assumption of CMR estimates is that there is uniform mixing of marked animals across the focal area. This was also validated using spatial data derived from images and linear models, a novel capability of the RPA technique. Our findings have the potential to improve wildlife monitoring techniques for fur seals and are broadly transferable to a wide range of other animal taxa where CMR techniques are employed. Furthermore, they add to the growing body of evidence that demonstrates the benefits of RPAs for wildlife monitoring exceed those of traditional techniques.

Operational Protocols for the Use of Drones in Marine Animal Research

“…In addition to reducing disturbance, drones also offer several advantages for data capture and research outcomes. The imagery captured creates a permanent record of the data, which reduces observer bias [97], it is faster than observer counts, so there is less time for individuals to move, and correctly captured data can also be used to create spatially accurate orthomosaics, digital surface models (DSMs), and 3-dimensional models for animal health metrics and condition assessment [98,99]. UAV pup counts also detected up to 32% more pups than observer counts [100].…”

Use of unmanned aerial vehicles (UAVs) for mark-resight nesting population estimation of adult female green sea turtles at Raine Island

“…A less invasive and more cost-effective approach is the mark-resight approach where marked animals are subsequently visually identified without the need for physical recapture [2]. Detection of animals with naturally identifying features or artificial marks can be enhanced by technologies such as unmanned aerial vehicles (UAVs) [3], camera traps [4], passive acoustics [5] and telemetry [6]. For example, infrared camera traps have been used for mark-resight surveys of snow leopards using distinct pelage patterns [7].…”

Uso de Aeronaves Remotamente Pilotadas (RPA) en la estimación de poblaciones de lobos marinos en la Isla Chincha sur - Ica

“…El empleo de RPA para el conteo de pinnípedos constituye un método seguro para el personal que lleva a cabo el trabajo de campo, que permitiría el acceso a localidades que por sus características topográficas en muchos casos son difíciles de evaluar, y con un mínimo de impacto sobre las poblaciones de lobos marinos. El uso de estas herramientas ha permitido obtener importantes beneficios para la gestión ambiental, que incluyen datos de abundancia con exactitud y precisión mejorados y menores sesgos, lo cual aumenta el poder estadístico para detectar las tendencias de la población (Hodgson et al, 2018, Sorrell et al, 2019, y sus patrones de distribución, herramientas relevantes para planificaciones futuras y gestión de manejo de fauna silvestre (Mulero-Pázmány et al, 2015).…”