Telemetry without collars: performance of fur- and ear-mounted satellite tags for evaluating the movement and behaviour of polar bears

The study of animal movement provides insights into underlying ecological processes and informs analyses of behaviour and resource use, which have implications for species management and conservation. The tools used to study animal movement have evolved over the past decades, allowing for data collection from a variety of species, including those living in remote environments. Satellite-linked radio and GPS collars have been used to study polar bear (Ursus maritimus) ecology and movements throughout the circumpolar Arctic for over 50 years. However, due to morphology and growth constraints, only adult female polar bears can be reliably collared for long durations. Further, collars have proven to be safe and reliable but there has been opposition to their use, resulting in a deficiency in data across much of the species’ range. To bolster knowledge of movement characteristics and behaviours for polar bears other than adult females, while also providing an alternative to collars, we tested the use of fur- and ear-mounted telemetry tags that can be affixed to polar bears of any sex and age. We also used data collected from the tags to quantify the amount of time subadult and adult males spent resting versus traveling while on land. Our results show fur tags remained functional for shorter durations than ear tags, but had comparable positional error estimates and provided sufficient data to model different behavioural states. Further, as hypothesized, subadult and adult male polar bears spent the majority of their time resting while on land, likely as a means of conserving energy until the sea ice reforms in early winter. Fur tags provide promise as a shorter-term means of collecting movement data from free-ranging polar bears.