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Researchers studied how eastern chimpanzees in Rwanda's cool montane Nyungwe National Park adjust their behavior in response to temperature and other climatic conditions. Using nearly 5,700 behavioral observations over one year, they found that chimpanzees adopt heat-conserving postures like curling and huddling when temperatures drop, and seek shade, descend from upper canopy layers, and shift to ground resting when temperatures rise. Temperature was the strongest predictor of these thermoregulatory behaviors, with wind speed also influencing canopy height selection, while rainfall and humidity showed weaker effects.
Why it matters
This research demonstrates that chimpanzees in cool montane environments employ flexible behavioral strategies to manage thermal challenges, expanding our understanding of great ape adaptation beyond the better-studied warm lowland habitats. These findings have implications for predicting how chimpanzee populations may respond to climate change, particularly in highland refugia that may become increasingly important for conservation.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Behavioral thermoregulation allows animals to reduce the physiological costs associated with variation in the thermal environment, yet little is known about how chimpanzees respond behaviorally to the cool and humid conditions of tropical montane forests. We examined how microclimatic conditions influenced resting posture, sun/shade use, substrate use, vertical position within the canopy, and day nest use in eastern chimpanzees (Pan troglodytes schweinfurthii) in Nyungwe National Park, Rwanda. From March 2024 to February 2025, we collected 5,661 individual behavioral records during 486 contact hours and paired behavioral observations with measurements of ambient temperature, water vapor pressure, wind speed, and rainfall. Bayesian mixed models showed that temperature was the most consistent climatic correlate of resting behavior. Under cooler conditions, chimpanzees were more likely to adopt heat conserving postures, particularly curled and huddled postures, and to use day nests. As temperature increased, chimpanzees increased their use of shade, shifted from arboreal to terrestrial resting, and used lower canopy strata more frequently. Higher wind speed was also associated with reduced use of the upper canopy, whereas rainfall, water vapor pressure, and fruit availability generally showed weaker or behavior-specific associations. These findings indicate that chimpanzees in a cool montane forest flexibly adjust posture, solar exposure, substrate use, vertical position, and day nest use in relation to local thermal conditions. Resting behaviour may therefore provide an important context for behavioral thermoregulation, extending our understanding of chimpanzee thermal ecology beyond the warmer lowland and savanna habitats that have received most previous attention.