Data: Seasonal activity patterns of a Kalahari mammal community: trade-offs between environmental heat load and predation pressure

Mammals in arid zones have to trade-off thermal stress, predation pressure, and time spent foraging in a complex thermal landscape. We quantified the relationship between the environmental heat load and activity of a mammal community in the hot, arid Kalahari Desert. We deployed miniature black globe thermometers within the existing Snapshot Safari camera trap grid on Tswalu Kalahari Reserve, South Africa. Using the camera traps to record species activity throughout the 24-hour cycle we quantified changes in the activity patterns of mammal species in relation to heat loads in their local environment. We compared the heat load during which species were active between two sites with differing predator guilds. In the presence of lion (Panthera leo) prey species were generally active under significantly higher heat loads, especially during the hot and dry spring. We suggest that increased foraging under high heat loads highlights the need to meet nutritional requirements while avoiding nocturnal activity when predatory pressures are high. Such a trade-off may become increasingly costly under the hotter and drier conditions predicted to become more prevalent as a result of climate change within the arid and semi-arid regions of southern Africa.

栖息于干旱地带的哺乳动物，需在热胁迫、捕食压力与觅食时长之间进行权衡，其生存环境为复杂的热景观格局。本研究针对炎热干旱的喀拉哈里沙漠中的哺乳动物群落，量化了环境热负荷与群落活动之间的关联。我们在南非茨瓦鲁喀拉哈里保护区（Tswalu Kalahari Reserve）现有的Snapshot Safari相机陷阱（camera trap）网格内布设了微型黑球温度计（black globe thermometer）。借助这些相机陷阱记录24小时周期内各物种的活动情况，我们量化了哺乳动物物种的活动模式随局部环境热负荷的变化规律。我们对比了两个捕食者类群（predator guild）存在差异的研究样地中，物种活动时所处的热负荷水平。在有狮子（Panthera leo）分布的样地中，猎物物种通常会在显著更高的热负荷下活动，这一现象在炎热干旱的春季尤为突出。我们推测，在高热负荷环境下增加觅食活动，体现了哺乳动物在规避捕食压力较高的夜间活动的同时，满足自身营养需求的生存策略。在南非南部干旱与半干旱地区，气候变化预计将使更炎热干旱的环境愈发普遍，在此类背景下，这类权衡取舍的成本或将愈发高昂。