Behavioral adjustments and support use of François' langur in limestone habitat in Fusui, China: Implications for behavioral thermoregulation

Abstract

Climatic factors such as temperature and humidity vary seasonally in primate habitats; thus, behavioral adjustments and microhabitat selection by primate species have been interpreted as behavioral adaptations. François' langur (Trachypithecus francoisi), a native species to southwest China and northern Vietnam, inhabits a limestone habitat with extreme climatic conditions. To understand the potential effects of climatic seasonality on this species, we collected data on the individual behavioral budgets in a T. francoisi group between January and December 2010 in Fusui County, China. Monthly, we performed 5–11 days of observation during this period, using focal animal sampling and continuous recording methods. We also recorded ambient temperature (Ta) and relative humidity (Hr) data at our study site. Results indicated that Ta and Hr were significantly correlated with each other and fluctuated dramatically on a daily, monthly, and seasonal basis. The amount of time spent resting, grooming, basking, and huddling also varied on a daily, monthly, and seasonal basis. The proportion of resting time and total sedentary activity time significantly increased at high and low Tas, respectively. The total sedentary time, resting time, and plant branch use all showed positive significant correlations with Ta. Our results suggest that behavioral adjustment and support use of T. francoisi, at least partly, were related to thermoregulation. T. francoisi minimized thermal stress through behavioral adjustments and support use. It is an adaptive behavior associated with the climatic extremes of limestone habitat. This study can potentially advise conservation management strategies in this specific habitat. Conservation efforts should focus on vegetation restoration in langurs' habitat, including those in the foothills.

Habitat use of the white‐headed langurs in limestone forest of Southwest Guangxi, China: Seasonality and group size effects

“…Consequently, time resting in shaded hillsides is helpful for the langurs to reduce body temperature. Similar behaviors are reported for other sympatric primates [e.g., François' langurs (Li et al, 2020) and Assamese macaques (Li et al, 2021)].…”

“…The dense vegetation on hillsides provides shade options for the langurs, particularly during hot and rainy months (Li et al, 2020). Primates frequently stay within the forest shade, avoiding daytime high temperatures and reducing their energetic thermoregulation demands (Duncan & Pillay, 2013; McFarland et al, 2020; Thompson et al, 2016).…”

“…Foraging on the cliffs is helpful for them to quickly sunbathe after feeding. Limestone-living primates generally sunbathe on bare rocks to save energy for thermoregulation during the winter (Li et al, 2020(Li et al, , 2021, and they likely do not have to travel from bare rocks/cliffs when young leaves and fruits are not available elsewhere, and adopt an energy-conservation strategy by reducing travel time when feeding on mature leaves (Li et al, 2019). Additionally, white-headed langurs inhabiting karst forests maintain a small home-range size with shorter daily path lengths during the dry months than during the rainy months, constituting an effective energy-conserving strategy (Huang et al, 2017;Zhou et al, 2011).…”

“…The dense vegetation on hillsides provides shade options for the langurs, particularly during hot and rainy months (Li et al, 2020).…”

Ticks, Hair Loss, and Non-Clinging Babies: A Novel Tick-Based Hypothesis for the Evolutionary Divergence of Humans and Chimpanzees

“…Decreased social grooming time with hair loss in hominins and increased social grooming time with hair preservation in chimpanzees may therefore represent divergent evolutionary responses following the LCA’s terrestrial exposure to ticks. Notably, gorillas and François’ langurs ( Trachypithecus francoisi ) have low social grooming times (1.3% and 1.2%, respectively) despite living on the ground (gorillas inhabit tropical forests [ 222 ], and François’ langurs inhabit tropical limestone cliffs [ 223 ]). These data suggest that these primates may not be exposed to large numbers of ticks in their local environments or that they have evolved alternative non-grooming anti-tick strategies that are currently unknown.…”