Where did the finch go? Insights from radio telemetry of the medium ground finch (Geospiza fortis)

Abstract

Movement patterns and habitat selection of animals have important implications for ecology and evolution. Darwin's finches are a classic model system for ecological and evolutionary studies, yet their spatial ecology remains poorly studied. We tagged and radio‐tracked five (three females, two males) medium ground finches ( Geospiza fortis ) to examine the feasibility of telemetry for understanding their movement and habitat use. Based on 143 locations collected during a 3‐week period, we analyzed for the first time home‐range size and habitat selection patterns of finches at El Garrapatero, an arid coastal ecosystem on Santa Cruz Island (Galápagos). The average 95% home range and 50% core area for G . fortis in the breeding season was 20.54 ha ± 4.04 ha SE and 4.03 ha ± 1.11 ha SE , respectively. For most of the finches, their home range covered a diverse set of habitats. Three finches positively selected the dry‐forest habitat, while the other habitats seemed to be either negatively selected or simply neglected by the finches. In addition, we noted a communal roosting behavior in an area close to the ocean, where the vegetation is greener and denser than the more inland dry‐forest vegetation. We show that telemetry on Darwin's finches provides valuable data to understand the movement ecology of the species. Based on our results, we propose a series of questions about the ecology and evolution of Darwin's finches that can be addressed using telemetry.

High-frequency GPS transmitters allow understanding of breeding shorebird movements and nest survival without human disturbance

“…Light-level geolocators have been used to monitor arrival and departure dates on the breeding grounds and nesting activity, but the information is subjective, especially in the Arctic where 24-hour sunlight makes locations inaccurate, and data are only collected if the bird returns, is recaptured, and the geolocator is retrieved , Burger et al 2012, Lagassé et al 2020. Conventional radio and archival GPS transmitters are used to measure a plethora of bird activity with several studies published specifically for the breeding season, but require time and effort to refind and minimal location data recorded (e.g., Bastian et al 2020, Musseau et al 2021, Beausoleil et al 2022. With recent advancements, HF-GPS tags are now small and capable enough to capture information at a finer temporal and spatial scale to monitor bird breeding movements.…”