Factors affecting location failure of GPS collars fitted to African leopards (Panthera pardus)

Recent technological advances in Global Positioning system (GPS) technology have generated an increase in the use of GPS collars fitted to wild animals to track their movements. GPS units are advantageous compared to other methods of remote tracking of animals in that the have the ability to gather large quantities of spatial data that may be accessed remotely. However, animal behaviour, topography, vegetation, and seasonality could all influence GPS acquisition success and therefore bias results from GPS technology. Here we analyse temporal and seasonal patterns associated with GPS acquisition failures in five GPS collars fitted to leopards (Panthera pardus) in the Waterberg region of South Africa. Of 6565 attempted GPS acquisitions, 19% (1236) failed with the location failure rate of individual collars ranging from 15-29%. Single failed attempts accounted for the majority of location failures, suggesting that failure was caused by temporary blockage to satellites. Failure rates were significantly higher during the day and there were indications that they were higher during the wet season than in the dry season. Failures were also clustered in space for some individual animals. Our results suggest that temporal patterns of animal behaviour and habitat choice influence the probability of GPS location failures in this species. We therefore suggest that potential biases should be accounted for when using GPS data to analyse movement and habitat selection in this and similar carnivore species.