Central to understanding animal ecology is how prey cope with the interacting risks of starvation and predation. This trade-off is modulated by the energy requirements of prey, yet relatively few studies have incorporated physiological mechanisms for energy savings when considering the behavioural response of prey to predation risk. In our study, we aimed to determine individual variation in behaviour, resting metabolism, body temperature and response to 24-h starvation within a captive population of fat-tailed dunnarts (Sminthopsis crassicaudata; 15-g insectivorous marsupials), and then, using semi-outdoor enclosures, test whether foraging effort and thermal energetics are adjusted in response to manipulation of ground cover, which for small mammals can simulate predation risk. We found that, under the low cover (high predation risk) treatment, dunnarts consumed less food and employed a greater daily reduction in body temperature between their active and rest phase. This result supports the hypothesis that rest-phase thermoregulatory energy savings are employed, even when food is available, if predation risk is perceived to increase the cost of foraging. Individuals exhibited correlated variation along two orthogonal axes incorporating the measured behavioural and metabolic variables, but these differences were not correlated with responses to starvation and predation risk. Our experiment demonstrates that flexibility in daily energy requirements provided by heterothermy can have important consequences for how small mammals respond to both starvation and predation risks. Such challenges are amplified in degraded habitat with introduced predators, making the capacity for heterothermy an even more important mechanism for survival.

中文翻译：

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小型，食虫性有袋动物的热能和行为，以应对饥饿和掠食的相互作用风险。

了解动物生态学的核心是猎物如何应对饥饿和捕食的相互作用风险。这种权衡是通过猎物的能量需求来调节的，但是考虑到猎物对捕食风险的行为响应，很少有研究纳入生理机制来节能。在我们的研究中，我们的目的是确定圈养的肥尾邓纳猪（Sminthopsis crassicaudata; 15 g食虫有袋动物）的行为，静息代谢，体温和对24小时饥饿的反应的个体差异，然后使用半-室外围栏，测试是否响应地面覆盖物的操作来调整觅食力和热能，这对于小型哺乳动物可以模拟掠食的风险。我们发现，在低掩盖（高捕食风险）治疗下，邓纳特人在活动和休息阶段之间消耗的食物更少，并且每天的体温降低幅度更大。该结果支持以下假设：即使认为有捕食风险也会增加觅食的成本，即使在有食物的情况下，也可以采用静止阶段的温度调节节能。个体在两个正交轴上表现出相关的变化，这些正交轴结合了所测得的行为和代谢变量，但这些差异与对饥饿和掠食风险的反应无关。我们的实验表明，异源热能提供的每日能量需求的灵活性可能会对小型哺乳动物如何应对饥饿和捕食风险产生重要影响。引入捕食者在退化的栖息地中加剧了此类挑战，