Department of Interdisciplinary Life Sciences, Research Institute of Wildlife Ecology, University of Veterinary Medicine, Savoyenstrasse 1, 1160, Vienna, Austria.
Department for Farm Animals and Veterinary Public Health, Institute of Animal Welfare Science, University of Veterinary Medicine, Veterinärplatz 1, 1210, Vienna, Austria.
J Comp Physiol B. 2023 Dec;193(6):689-697. doi: 10.1007/s00360-023-01512-6. Epub 2023 Sep 24.
The wild boar (Sus scrofa) originates from warm islands but now inhabits large areas of the world, with Antarctica as the only continent not inhabited by this species. One might be tempted to think that its wide distribution results from increasing environmental temperatures. However, any effect of temperature is only indirect: Abundant availability of critical food resources can fully compensate the negative effects of cold winters on population growth. Here, we asked if temperature as a habitat factor is unimportant compared with other habitat indices, simply because wild boars are excellent thermoregulators. We found that the thermoneutral zone in summer was approximately 6-24 °C. In winter, the thermoneutral zone was lowered to 0-7 °C. The estimated increase in the heart rate and energy expenditure in the cold was less than 30% per 10 °C temperature decline. This relatively small increase of energy expenditure during cold exposure places the wild boar in the realm of arctic animals, such as the polar bear, whereas tropical mammals raise their energy expenditure several fold. The response of wild boars to high T was weak across all seasons. In the heat, wild boars avoid close contact to conspecifics and particularly use wallowing in mud or other wet substrates to cool and prevent hyperthermia. Wild boars also rely on daily cycles, especially of rhythms in subcutaneous temperature that enables them to cheaply build large core-shell gradients, which serve to lower heat loss. We argue it is predominantly this ability which allowed wild boars to inhabit most climatically diverse areas in the world.
野猪（Sus scrofa）起源于温暖的岛屿，但现在却分布在世界的大片地区，南极洲是唯一没有这种物种栖息的大陆。人们可能会认为，它的广泛分布是由于环境温度的升高所致。然而，温度的任何影响都是间接的：大量关键食物资源的存在可以完全弥补寒冷冬季对种群增长的负面影响。在这里，我们想知道与其他栖息地指数相比，温度作为一个栖息地因素是否不重要，仅仅是因为野猪是优秀的体温调节者。我们发现，野猪在夏季的舒适温度区约为 6-24°C。在冬季，舒适温度区下降到 0-7°C。在寒冷环境中，心率和能量消耗的估计增加量不到每 10°C 温度下降的 30%。这种在寒冷环境中能量消耗的相对较小增加使野猪处于北极动物的范畴内，例如北极熊，而热带哺乳动物则将其能量消耗提高了数倍。野猪对高温的反应在所有季节都很微弱。在炎热的天气中，野猪避免与同类密切接触，特别喜欢在泥或其他湿基质中打滚以降温并防止体温过高。野猪还依赖于日常节律，尤其是皮下温度的节律，这使它们能够廉价地建立大的核心-壳梯度，从而降低热量损失。我们认为，正是这种能力使野猪能够栖息在世界上气候最多样化的地区。
