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Thermal constraints on energy balance, behaviour and spatial distribution of grizzly bears
Functional Ecology ( IF 5.2 ) Pub Date : 2021-01-10 , DOI: 10.1111/1365-2435.13727
Savannah A. Rogers 1 , Charles T. Robbins 2 , Paul D. Mathewson 3 , Anthony M. Carnahan 4 , Frank T. Manen 5 , Mark A. Haroldson 5 , Warren P. Porter 3 , Taylor R. Rogers 6 , Terence Soule 6 , Ryan A. Long 1, 7
Affiliation  

  1. Heat dissipation limit theory posits that energy available for growth and reproduction in endotherms is limited by their ability to dissipate heat. In mammals, endogenous heat production increases markedly during gestation and lactation, and thus female mammals may be subject to greater thermal constraints on energy expenditure than males. Such constraints likely have important implications for behaviour and population performance in a warming climate.
  2. We used a mechanistic simulation model based on the first principles of heat and mass transfer to study thermal constraints on activity (both timing and intensity) of captive female grizzly bears Ursus arctos in current and future climate scenarios. We then quantified the relative importance of regulatory behaviours for maintaining heat balance using GPS telemetry locations of lactating versus non‐lactating female bears from Yellowstone National Park, and assessed the degree to which costs of thermoregulation constrained the distribution of sampled bears in space and time.
  3. Lactating female bears benefitted considerably more from behavioural cooling mechanisms (e.g. partial submersion in cool water or bedding on cool substrate) than non‐lactating females in our simulations; the availability of water for thermoregulation increased the number of hours during which lactating females could be active by up to 60% under current climatic conditions and by up to 43% in the future climate scenario. Moreover, even in the future climate scenario, lactating bears were able to achieve heat balance 24 hr/day by thermoregulating behaviourally when water was available to facilitate cooling.
  4. The most important predictor of female grizzly bear distribution in Yellowstone, regardless of reproductive status, was elevation. However, variables associated with the thermal environment were relatively more important for predicting the distribution of lactating than non‐lactating female bears.
  5. Our results suggest that the costs of heat dissipation, which are modulated by climate, may impose constraints on the behaviour and energetics of large endotherms like grizzly bears, and that access to water for cooling will likely be an increasingly important driver of grizzly bear distribution in Yellowstone as the climate continues to warm.


中文翻译:

热约束对灰熊的能量平衡,行为和空间分布的影响

  1. 散热极限理论认为,吸热中可用于生长和繁殖的能量受其散热能力的限制。在哺乳动物中,内源性产热在妊娠和哺乳期间显着增加,因此雌性哺乳动物可能比雄性受到更大的能量消耗热量约束。在气候变暖的情况下,这些限制可能会对行为和人口表现产生重要影响。
  2. 我们使用了基于传热传质第一原理的机械模拟模型,研究了当前和未来气候情景中圈养雌性灰熊熊熊活动的热约束(时间和强度)。然后,我们使用GPS遥测技术对黄石国家公园的哺乳母熊和非哺乳母熊量化了调节行为对于维持热量平衡的相对重要性,并评估了温度调节成本限制了采样熊在时空上的分布的程度。
  3. 在我们的模拟中,哺乳雌性熊从行为降温机制(例如,部分浸没在冷水中或在凉爽基质上被褥)中获得的收益要大于非哺乳雌性。在目前的气候条件下,用于调节温度的水可增加哺乳期女性活跃的小时数,最多可延长60%,而在未来的气候情景中,则可延长多达43%。此外,即使在未来的气候情景中,在有水可促进冷却的情况下,泌乳熊也能够通过行为调节温度来实现24小时/天的热量平衡。
  4. 无论繁殖状况如何,黄石雌性灰熊分布的最重要预测因子是海拔。但是,与热环境有关的变量比非哺乳母熊在预测哺乳期的分布方面更为重要。
  5. 我们的结果表明,受气候调节的散热成本可能会限制诸如灰熊之类的大型吸热行为和能量,而获得冷却水的使用将可能成为灰熊分布中日益重要的驱动因素。黄石随着气候持续变暖。
更新日期:2021-02-04
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