Absence of negative effect of GPS-tags on survival and breeding success in a long-lived territorial raptor

Abstract

GPS tracking has enabled significant advances in the study of animal movements such as migration and habitat use. However, GPS devices can affect the behaviour of tagged individuals, especially for flying animals such as birds, and may ultimately impair their reproduction and/or survival. While numerous studies have investigated the potential negative effects of GPS-tags on birds, few have simultaneously looked at these effects on reproduction and survival, with studies on the latter sometimes suffering from methodological flaws. This study investigated the effects of GPS-tagging on the breeding success and survival of a medium-sized raptor, Bonelli's Eagle Aquila fasciata. Forty-five breeding adults were equipped with backpack-mounted GPS-tags representing 1.2–3.5% of individual body mass. Using a recently developed capture–mark–recapture model that accounts for differences in detectability between types of tags (metal ring, coloured ring or GPS), our results showed no significant differences in survival or breeding success between GPS-tagged and banded individuals. Overall, we did not observe deleterious effects of GPS-tagging on Bonelli's Eagle that would warn against the use of GPS-tags in this species, or other medium-to-large raptors, given the relevant information they might provide for conservation.