Rainfall， temperature， and habitat resources are essential for the survival of animals in arid ecosystems， but the responses of the same species to these factors on a larger spatial scale are not clear. Orientallactaga sibirica is a widely distributed rodent in arid areas， and its living conditions can sensitively reflect climate change and habitat resource changes. It is of great significance to reveal the environmental adaptability of small mammals by studying the effects of environmental changes on the body size of O. sibirica. In this study， from June to August 2019， samples were collected by net capture method in the main distribution area of the O. sibirica. The body weight was weighed， and the δ¹³C and δ¹⁵N values of muscle tissue were measured. The effects of annual average temperature， annual precipitation and normalized difference vegetation index （NDVI） on these indicators were explored. The results showed that the body weight of O. sibirica decreased significantly with the increase of annual average temperature （P0.01）. The annual precipitation was significantly negatively correlated with the δ¹³C and δ¹⁵N of muscle tissue （P0.01）. The segmented structural equation model analysis showed that the annual precipitation had a significant negative effect on the body weight of O. sibirica through NDVI and δ¹³C and δ¹⁵N （P0.05）. Thus， the body weight and feeding habits of O. sibirica adaptively adjusted with habitat changes.

Orientallactaga sibirica  /  Stable isotope  /  Mean annual temperature  /  Annual precipitation  /  NDVI