Food availability, temperature, and day length drive seasonal variations in the positional behavior of white-headed langurs in the limestone forests of Southwest Guangxi, China

Information on positional behavior contributes to the understanding of the ecological adaptation mechanisms in animals. We collected data on the positional behavior of white-headed langurs (Trachypithecus leucocephalus) at the Guangxi Chongzuo White-Headed Langur National Nature Reserve from September 2016 to August 2017 via instantaneous scan sampling method. This study aimed to examine the importance of positional behavior flexibility in limestone forests characterized by seasonal variations in climate and food resources. Our results indicated that langurs adopted leaping (47.92% +/- 5.50%) and vertical climbing (40.13% +/- 6.20%) as their predominant locomotor modes and sitting (83.08% +/- 4.70%) as their predominant posture. Their positional behavior exhibited marked seasonal variations. More specifically, langurs used quadrupedal walking more frequently during the dry season than during the rainy months. In the stationary state, they sat more frequently during the dry season, whereas they laid and suspended more often during the rainy season. Their positional behavior was affected by fruit availability, day length, and temperature. Quadrupedal walking increased with the decrease in fruit availability, whereas leaping was positively correlated with fruit availability. Moreover, sitting was positively correlated with average temperature but negatively correlated with day length. Lying was also negatively correlated with temperature but positively correlated with day length. We conclude that white-headed langurs adapt to limestone forests with positional behavior flexibility in response to seasonality. Our research provides evidence of the effects of food availability, ambient temperature, and day length on the positional behavior of white-headed langurs, highlighting the need to understand their behavioral ecology and the influence of ecological factors on behavioral adaptation.