How energy and thermal landscapes influence habitat use in chacma baboons (Papio ursinus)

Abstract

Landscape heterogeneity drives chacma baboon movement, behaviour and habitat use. Here, baboons alter their responses to the changing environment to balance thermoregulation and resource acquisition. This study incorporated historical data from multiple habituated troops within the Swebeswebe Wildlife Estate, along with more current field data collected while following a troop of 69 individuals. Behavioural data were collected in 30-minute scan sampling intervals to assess activity budgets and shade use, while corresponding GPS data tracked movement. Climatic conditions were recorded through an onsite weather station along with miniglobe thermometers placed in representative microhabitats, including one carried while tracking the troop. Landscape features, and food and water availability were mapped to analyse how biotic and abiotic factors influenced troop movement, behaviour and habitat use. Baboons travelled further under high heat loads and low water availability. They, however, only expanded their home ranges, particularly along the main river system, during periods of water scarcity. In contrast to travel distance, the frequency of travel behaviour, as well as rest behaviour, increased with higher temperatures and water availability. As a result, a trade-off was observed in foraging behaviour, highlighting prioritisation between thermoregulation and energy acquisition with differing environmental drivers. Social behaviour decreased under higher water availability but, in contrast, increased with higher vegetation greenness. Vegetation greenness was a key driver to shade use, a behaviour critical for thermoregulation, particularly under higher heat loads. In line with thermoregulatory activity, baboons selected stable microclimates, preferring cooler, densely vegetated habitats, particularly during peak heat loads in the day and in the wet season. Baboon distribution shifted seasonally, with troops found closer to their main cave sleep site and rivers during the dry season and being found further away from fence lines. This indicated a more constrained spatial use pattern in times of resource scarcity. These findings highlight the flexible responses of baboons to thermal and resource landscapes. The understanding of these patterns is crucial for their conservation through the protection of heterogeneous landscapes, and a broader understanding of their ecological resilience in the face of worsening climate change.