McNamara J M, Houston A I
EGI, Department of Zoology, Oxford.
Acta Biotheor. 1990 Mar;38(1):37-61. doi: 10.1007/BF00047272.
It is shown that in a range of models, the probability that a forager dies from starvation is, to a good approximation, an exponential function of energy reserves. Using a time and energy budget for a 19g passerine, we explore the consequences, in terms of starvation and predation, of various levels of energy reserves. It is shown that there exists an optimal level L* of reserves at which total mortality (starvation plus predation) is minimized. L* increases when the environment deteriorates as a result of a decrease in either temperature or mean gross gain or an increase in the mean search time. The effect of combined deteriorations is greater than the sum of their individual effects. At L*, the probability of predation is much higher than the probability of starvation. A simple analytic model suggests that this result will be fairly general, but also indicates conditions under which the result might not hold.
结果表明，在一系列模型中，觅食者死于饥饿的概率在很大程度上近似于能量储备的指数函数。利用一只19克重雀形目鸟类的时间和能量预算，我们从饥饿和捕食的角度探讨了不同能量储备水平的后果。结果表明，存在一个最优储备水平L*，在这个水平下总死亡率（饥饿加捕食）最小。当环境因温度降低、平均总增益减少或平均搜索时间增加而恶化时，L会增加。综合恶化的影响大于其各自影响的总和。在L时，被捕食的概率远高于饥饿的概率。一个简单的分析模型表明，这个结果相当普遍，但也指出了该结果可能不成立的条件。
