Pierce G J, Ollason J G, Speirs D C
Department of Zoology, University of Aberdeen, Aberdeen, UK.
Culterty Field Station, University of Aberdeen, Newburgh, Ellon, Aberdeenshire, UK.
Behav Processes. 1993 Apr;29(1-2):65-84. doi: 10.1016/0376-6357(93)90028-P.
Common shrews (Sorex araneus L.) were presented with two prey types at various densities in a depleting environment. Observed diet choice was compared to predictions of the classical optimal diet model and of "shrew-specific" simulations incorporating patch depletion. Two strategies were simulated: expansion of the diet from taking only profitable prey to taking both types, and fixed partial preference. The simulations predict partial preference over a narrow range of initial densities of profitable prey. However, within this range, energetic benefits are relatively insensitive to diet composition. Shrews preferred more profitable prey and were more selective when encounter rate with profitable prey was higher, broadly as predicted by all the models. Partial preference was observed, but neither of the mechanisms simulated was strongly supported by results for the shrews. Univariate and multivariate analyses were used to identify cues involved in selecting prey. Instantaneous measures of encounter rates and encounters per unit search distance were the best predictors of subsequent prey choice, but decisions appear to have been made on a probabilistic basis.
在资源逐渐减少的环境中，向普通鼩鼱（Sorex araneus L.）提供两种不同密度的猎物类型。将观察到的饮食选择与经典最优饮食模型以及纳入斑块消耗的“鼩鼱特定”模拟预测进行比较。模拟了两种策略：饮食从仅捕食有利可图的猎物扩展到捕食两种类型的猎物，以及固定的部分偏好。模拟预测在有利可图猎物的初始密度较窄范围内存在部分偏好。然而，在此范围内，能量收益对饮食组成相对不敏感。鼩鼱更喜欢更有利可图的猎物，并且当与有利可图猎物的相遇率较高时更具选择性，这大致与所有模型的预测一致。观察到了部分偏好，但鼩鼱的结果并未强烈支持所模拟的两种机制中的任何一种。使用单变量和多变量分析来识别参与选择猎物的线索。相遇率的即时测量和每单位搜索距离的相遇次数是后续猎物选择的最佳预测指标，但决策似乎是基于概率做出的。
