Credit: Kristin Laidre
Telemetry has played an important role in polar bear research with the first use starting in the 1970s with very high frequency transmitters (VHF) being used to track movements. The detriment of this technology is the need to be in close proximity to receive a signal and this often necessitates the use of aircraft. Advances in telemetry resulted in satellite-linked radio tags first being used in 1977 on polar bears. Their adoption as a primary research tool quickly became entrenched to study movements, habitat use, climate change impacts, phenology, population boundaries, survival estimation, reproductive success, physiology, to aid population estimation, and understand the potential impacts of development.
Two forms of determining position from satellite-linked telemetry exist: Doppler shift and geographic positioning system (GPS). Doppler shift was used in earlier studies and provide less precise locations (to within 2 km) but it is still used in small transmitters. GPS-based telemetry developed in the 1990s and provides very precise locations (to within several meters) and is now commonly used in most studies. Attachment of transmitters to polar bears has usually involved collars but due to males having necks wider than their heads, they cannot wear collars so studies have largely been restricted to adult females. Some subadults have been collared but there are risks associated with growing bears. Collars usually include to break-away mechanisms: an electronic release with a pre-set date to open and allow the collar to drop off and a mechanic release associated with erosion of components that allow release. Eartag transmitters are commonly used for subadults and adult males. These small transmitters rely on Doppler-shift locations and usually provide one location/day for up to 6 months. In contrast, GPS-collars can provide up to 24 locations/day, although six locations is more common, and can provide up to 2 years of transmissions. Other attachment methods have been used with small transmitters being epoxied onto fur, which allows for several weeks or months of data collection. More recently, attempts to develop a burr-on-fur attachment is being explored as a less-invasive alternative to glue-on methods.
All five nations with polar bears have used satellite-linked telemetry to study polar bears. The information gained from this technology has fundamentally rewritten our understanding of their ecology. Deployment of telemetry devices requires the physical capture of polar bears and opposition to do so has arisen but the methods have few impacts and studies have revealed no negative long-term effects of handling. As a primary tool in the research of polar bears, the use of telemetry, as in many other wildlife species, is a cornerstone that aids their management and conservation.
- Laidre KL, Durner GM, Lunn, NJ, Regehr EV, Atwood TC, Rode KD, Aars J, Routti H, Wiig Ø, Dyck M, Richardson ES, Atkinson S, Belikov S, and Stirling I. 2022. The role of satellite telemetry data in 21st century conservation of polar bears (Ursus maritimus). Frontiers in Marine Science 9.816666, https://www.frontiersin.org/articles/10.3389/fmars.2022.816666/full.