Temperatures in arctic-boreal regions are increasing rapidly and pose significant challenges to moose (Alces alces), a heat-sensitive large-bodied mammal. Moose act as ecosystem engineers, by regulating forest carbon and structure, below ground nitrogen cycling processes, and predator-prey dynamics. Previous studies showed that during hotter periods, moose displayed stronger selection for wetland habitats, taller and denser forest canopies, and minimized exposure to solar radiation. However, previous studies regarding moose behavioral thermoregulation occurred in Europe or southern moose range in North America. Understanding whether ambient temperature elicits a behavioral response in high-northern latitude moose populations in North America may be increasingly important as these arctic-boreal systems have been warming at a rate two to three times the global mean. We assessed how Alaska moose habitat selection changed as a function of ambient temperature using a step-selection function approach to identify habitat features important for behavioral thermoregulation in summer (June–August). We used Global Positioning System telemetry locations from four populations of Alaska moose (n = 169) from 2008 to 2016. We assessed model fit using the quasi-likelihood under independence criterion and conduction a leave-one-out cross validation. Both male and female moose in all populations increasingly, and nonlinearly, selected for denser canopy cover as ambient temperature increased during summer, where initial increases in the conditional probability of selection were initially sharper then leveled out as canopy density increased above ~ 50%. However, the magnitude of selection response varied by population and sex. In two of the three populations containing both sexes, females demonstrated a stronger selection response for denser canopy at higher temperatures than males. We also observed a stronger selection response in the most southerly and northerly populations compared to populations in the west and central Alaska. The impacts of climate change in arctic-boreal regions increase landscape heterogeneity through processes such as increased wildfire intensity and annual area burned, which may significantly alter the thermal environment available to an animal. Understanding habitat selection related to behavioral thermoregulation is a first step toward identifying areas capable of providing thermal relief for moose and other species impacted by climate change in arctic-boreal regions.

中文翻译：

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大型北方食草动物的行为改变以缓解变暖条件

北极-寒带地区的气温正在迅速上升，并对驼鹿（Alces alces）这种对热敏感的大型哺乳动物构成了重大挑战。驼鹿充当生态系统工程师，通过调节森林碳和结构、地下氮循环过程和捕食者-猎物动态。先前的研究表明，在较热的时期，驼鹿对湿地栖息地的选择更强，森林树冠更高更密，并最大限度地减少了太阳辐射的暴露。然而，先前关于驼鹿行为体温调节的研究发生在欧洲或北美的南部驼鹿范围内。了解环境温度是否会引起北美高北纬驼鹿种群的行为反应可能变得越来越重要，因为这些北极-寒带系统的变暖速度是全球平均水平的两到三倍。我们使用步进选择函数方法评估了阿拉斯加驼鹿栖息地选择如何随环境温度而变化，以识别对夏季（6 月至 8 月）行为体温调节重要的栖息地特征。从 2008 年到 2016 年，我们使用了来自四个阿拉斯加驼鹿种群（n = 169）的全球定位系统遥测位置。我们使用独立标准下的准似然评估模型拟合并进行留一交叉验证。所有种群中的雄性和雌性驼鹿都越来越多地，非线性地，随着夏季环境温度的升高，选择更密集的冠层覆盖，其中选择条件概率的初始增加最初更剧烈，然后随着冠层密度增加到约 50% 以上而趋于平稳。然而，选择反应的幅度因人口和性别而异。在包含两性的三个种群中的两个中，雌性在更高的温度下对更密集的树冠表现出比雄性更强的选择反应。我们还观察到，与阿拉斯加西部和中部的种群相比，最南端和最北端的种群具有更强的选择反应。北极-寒带地区气候变化的影响通过增加野火强度和年度燃烧面积等过程增加了景观的异质性，这可能会显着改变动物可利用的热环境。