PREDATION RISK AND UNPREDICTABLE FEEDING CONDITIONS - DETERMINANTS OF BODY-MASS IN BIRDS
PREDATION RISK AND UNPREDICTABLE FEEDING CONDITIONS - DETERMINANTS OF BODY-MASS IN BIRDS
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DOI：
10.2307/1938580
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发表时间：
1986-04-01
期刊：
影响因子：
4.8
通讯作者：
LIMA, SL
中科院分区：
文献类型：
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作者：
LIMA, SL
越冬鸟类所保持的体重（或脂肪储备）可以被视为饥饿风险和捕食风险之间的权衡。这是因为脂肪储备以非常不同的方式影响生存。从饥饿的角度来看，一只鸟应该尽可能的胖（或重），以尽量减少在天气相关的食物不可用期间饥饿的可能性，因为胖的鸟可以在没有食物的情况下比瘦的鸟存活更长时间。然而，从捕食风险的角度来看，鸟应该尽可能瘦，以尽量减少被杀的可能性。较瘦的鸟类比较重的鸟类的生存成本更低，因此花费更少的时间进食，可能暴露于捕食者。此外，瘦鸟可能更善于逃脱捕食者一旦攻击。如果一只鸟试图在冬季最大限度地减少死亡的可能性，那么它所保持的脂肪储备和体重将反映出饥饿和捕食风险之间的权衡。一个简单的随机模拟模型开发，以探索这种权衡的性质表明，体重应该：（1）增加的频率和/或苛刻的时期的食物不可用（由于雪，冰，风等）; (2)随着捕食风险的增加而减少;（3）随着温度的升高而减少;（4）随着食物丰富而增加。对模型的分析很容易解释为什么越冬鸟类的脂肪水平低于它们的能力。在更北的种群中和在仲冬期间，一个给定鸟类物种的个体更重的趋势也很容易根据上述权衡来解释。越冬鸟类觅食行为和种群调节的影响进行了讨论。
The body mass (or fat reserves) maintained by a wintering bird can be viewed as a trade-off between the risk of starvation and the risk of predation. This follows from the fact that fat reserves affect survival in very different ways. From the starvation point of view, a bird should be as fat (or heavy) as possible in order to minimize its probability of starvation during weather-related food unavailability because fatter birds can survive longer without food than leaner birds. From the predation risk point of view, however, a bird should be as lean as possible to minimize its probability of being killed. Leaner birds will incur a smaller cost of existence than heavier birds and thus spend less time feeding, potentially exposed to predators. In addition, lean birds are likely to be more adept at escaping predators once attacked. If a bird is attempting to minimize its probability of death during the winter season, the fat reserves and thus the body mass it maintains will reflect a trade-off between starvation and predation risk. A simple stochastic simulation model developed to explore the nature of this trade-off indicates that body mass should: (1) increase with the frequency and/or harshness of periods of food unavailability (due to snow, ice, wind, etc.); (2) decrease with increasing predation risk; (3) decrease with increasing temperature; and (4) increase with food abundance. The analysis of the model readily explains why wintering birds maintain fat levels lower than those of which they are capable. The tendency for individuals of a given bird species to be heavier in more northerly populations and during midwinter is also readily interpreted in terms of the above tradeoff. Implications for foraging behavior and population regulation in wintering birds are discussed.