Effects of moose movement and habitat use on GPS collar performance

We tested a radiotelemetry collar that uses a Global Positioning System (GPS) unit to calculate animal locations. We placed the collar in a range of cover types and compared locations reported by the collar to differentially- corrected GPS locations. We placed the collar on a free-ranging moose (Alces alces) and determined how selection of cover types, collar movement, and collar orientation affected GPS locations. On or off the moose, the GPS unit collected a location in >90% of location attempts in areas with no or thin canopy cover, including mature deciduous canopies in winter. Under a mature conifer canopy or a mature deciduous canopy in summer, 60 to 70% of location attempts were successful. Locations from the GPS unit in the collar were close to the expected precision of non-differentially corrected GPS (within 40 m 50% of the time and 100 m 95% of the time). Locations did not have a directional bias. Movement of the moose while a location was being attempted did not affect GPS locations. The moose occasionally laid down so the collar was horizontal. Although this decreased the success of location attempts, <1% of location attempts were so affected. GPS radiotelemetry has great promise for expanding our knowledge about hourly, daily, and annual patterns in animal movements and habitat selection.