Population density and activity of the Gobi bear

Abstract

The Gobi bear (Ursus artcos gobiensis), a subspecies endemic to the Mongolian Gobi desert, is one of the most endangered brown bear subspecies due to isolation and low population abundance. Therefore assessing its population density is crucial for effective conservation. In 2020 we deployed 36 camera traps in 35 sites for three months (March to June) covering an area of ~ 725 km2 and totalling 2302 camera-days. We collected 68 bear detections from which 51 served to identify five bears using natural marks in addition to ear-tags and a radio-collar on two individuals, respectively. Notably, the majority of the detection (n = 53) arose from a single camera location located near a water hole. We used the random-thinning SCR (rtSCR) model to estimate the population density and we further investigated the activity pattern by using the timestamp of each detection. Population density was D = 1.92/1000 km2 (95% BCI = 0.77 – 3.88) with 𝜎 = 5.37 km (95% BCI = 4.03 – 7.2) while population abundance was N = 16.94 (95% BCI = 7 – 35). Activity level was 0.39 (95% CI = 0.26 – 0.54), mostly concentrated before sunrise and after sunset, and Nocturnal was the most supported diel niche model using the Maximizing hypothesis set. This study represents the first attempt to estimate the population density of Gobi bears using camera-trapping and provides valuable insights into their springtime activity patterns and sociality. Moreover, we offer suggestions for future camera-trapping surveys, specifically tailored to optimise Gobi bear research and conservation efforts.