Difference of habitat suitability and the influencing variables between winter and summer of Procapra picticaudata in the Three-River-Source region, China.

Procapra picticaudata is an ungulate endemic to the Tibetan Plateau and is widely distributed in the Three-River-Source region. Predicting the seasonal variations in habitat suitability and understanding the effects of environmental variables on habitat use by this species will help formulate effective conservation strategies and clarify its niche characteristics. Based on point records of the occurrence collected during repeated field surveys in winter (January 2019) and summer (August 2019), we used MaxEnt model to predict the differences in habitat suitability and the distribution pattern of the P. picticaudata in the Three-River-Source region using eight preselected environmental variables. We further explored the influence of those variables on the P. picticaudata' distribution pattern using environmental response curves. The results showed that the average area under the receiving operator curve values in winter and summer was 0.901±0.023 and 0.882±0.024, respectively, with a good accuracy of fitness. The total area of suitable habitat for P. picticaudata in winter and summer was 6.83×10⁴ and 9.78×10⁴ km², respectively. The area of suitable habitats in summer increased significantly compared with winter. There was a tendency for P. picticaudata to spread to the south of the Yangtze River Source Park and the Yellow River Source Park in summer. The spatial patterns of habitat suitability in both winter and summer took Three-River-Source National Park as the high-value center and decreased around it. The seasonal average temperature, altitude, population density, and slope were the main environmental variables affecting the distribution of P. picticaudata both in winter and summer. The higher temperatures in summer allowed the suitable P. picticaudata habitats to extend into areas above 5000 m in altitude, and to areas with slopes of less than 25°, compared with winter. The expansion of human activities in summer encroached on the suitable habitat of P. picticaudata.