Combining distance sampling and resource selection functions to monitor and diagnose declining Arabian gazelle populations

Arabian gazelle Gazella arabica are experiencing a rapid decline in Arabia. Action is required to help detect declines and diagnose the threats responsible, so that conservation areas can better manage resources to protect gazelle. To develop a gazelle monitoring system for As Saleel Natural Park, Oman, Arabian gazelle were surveyed using distance sampling in 2014 and 2015. The surveys showed a significant decline in gazelle numbers from 1198 +/- 224 gazelle in 2014 to 748 +/- 147 in 2015. To help diagnose the causes of the decline we created resource selection functions (RSFs) using the survey point data. RSF models clearly showed that gazelle avoided human disturbances, strongly avoiding livestock structures inside As Saleel, and the protected area boundary itself. The avoidance response effectively removed habitat from gazelle use. Our data indicated the decline of gazelle was the result of the aforementioned disturbances, and a road construction project within As Saleel between the two surveys. Our results show the benefits of combining distance sampling with RSFs. The technique provides robust information and results that can guide reserve management and steer conservation actions. We recommend this technique for monitoring gazelles and other species that can be surveyed using distance sampling.