Factors affecting recent population decline and range contraction of the greater long-tailed hamster in China.

Context. Over the past few decades, many mammalian species have experienced range shifts, due to either local extinction or expansion, under accelerating global climate change. However, the distinct effects and ecological mechanisms behind the anthropogenic and climate pressures on range shifts have not been fully studied. Aims. Our aim was to examine the impacts of climate warming and human disturbance on the local disappearance probability and northwards range contraction at the southern distribution boundary of the greater long-tailed hamster (Tscherskia triton), a rodent pest, in northern China. The assessment was based on historical records from 1963 to 2018. Methods. Logistic generalised additive models were used to quantify the association between local disappearance probability and environmental variables in the greater long-tailed hamsters. The air temperature threshold for local disappearance of the greater longtailed hamsters (defined as the disappearance threshold) was estimated using the year following the last observation year. We also predicted changes in the distribution of the greater longtailed hamsters under future warming scenarios. Key results. The greater long-tailed hamster population has experienced notable population decline and range contraction along its southern boundary during the past 48 years. The probability of local disappearance is closely associated with climate warming (indexed by the annual air temperature), drought (indexed by annual precipitation), and human disturbance (indexed by the population density). The threshold of the yearly maximum temperature for local disappearance was 15.8 ± 3.87°C, and the average maximum temperature of the warmest months (from June to August) was 28.21 ± 2.71°C. Our projection model indicates that ongoing climate warming will cause more range contraction of the plain areas at the southern boundary of the greater long-tailed hamster distribution. Conclusions. Over recent decades, rapid climate change and human disturbance have been associated with population decline and northwards range contraction of the southern boundary for the greater long-tailed hamster population in China. Implications. Our study has significant implications for managing the damage done to farmland crops by this species, as well as the future conservation of this species in natural ecosystems. [ABSTRACT FROM AUTHOR]