Abstract
Food habits are important factors in the adaptation of wild nonhuman primates. White-headed langurs (Trachypithecus leucocephalus) are endemic to heavily fragmented limestone forests and adapt to unique living environments via flexible food selection strategies. In this study, we compared the dietary data for white-headed langurs living in Chongzuo White-headed Langur National Nature Reserve in 2013 and 2016 to evaluate interannual variations in diet. Our results indicated that young leaves were the main food source for langurs, accounting for 52.4% (SD 25.4%) and 65.2% (SD 22.4%) of their diet in 2013 and 2016, respectively. The pattern of plant part consumption was similar between the two years. The consumption of young leaves varied with the availability of young leaves, whereas the consumption of mature leaves was negatively correlated with young leaf availability. The consumption of plant species and diet diversity were higher in 2013 than in 2016. In both 2013 and 2016, although diet diversity varied with the consumption of mature leaves, it was negatively correlated with the consumption and availability of young leaves. Dietary interannual variation is likely to either be linked to phenological variations or indicate that white-headed langurs have a flexible ecological adaptation coping with habitat fragmentation.