2.1 Study site and subject
The research was conducted on François’ langur at ECNNR, Guangxi Province, China (22°36’32”–22°49’53”N, 106°58’12”–107°15’45”E; Figure 1). The main study site was a 258.196 km2 karst hill, which is located at an elevation of 300 to 700 m above sea level. From July 2019 to June 2020, the mean minimum and maximum temperatures were approximately 10.22 and 34.28 °C, respectively (n = 10, the annual average temperature is 22.37 °C). The total annual precipitation at the site during the study period was 1,462.9 mm, with 83.2% of the rain falling between April and September (Figure 2). There was a dry (October to March) and wet season (April to September) based on the precipitation distribution. One group of François’ langur was monitored, which was composed of six individuals (two adult males and four adult females) at the beginning of the study period and increased to eight individuals due to the birth of two infants by the end of the study period.