An optimal habitat-selecting organism should use a dispersal strategy that enables occupation of the habitat yielding greatest fitness. The strategy is complicated when habitat quality varies through time. Theory predicts that the long-term distribution of individuals will match mean habitat quality while undermatching current habitat quality. I tested the prediction with experiments on controlled populations of meadow voles occupying two pairs of field enclosures. I released equal numbers, and equal sexes, of voles in each enclosure, and varied resource abundance between enclosures by supplemental feeding. I measured the voles' response with giving-up densities (GUDs) in artificial foraging patches, and with live-trapping at the end of the experiment. The data were consistent with only one of four a priori dispersal models. Giving-up densities declined with resource supply because short-term supply had no effect on population density. GUDs were invariant to the time-course of the experiment because densities were proportional to each enclosure's long-term mean quality. Similar patterns in sex ratios and patterns of habitat occupation by juvenile voles born during the experiment reinforce the interpretation of time-averaged habitat matching. This study adds to the cumulating evidence that strategies of space use converge towards behavioral and evolutionary optima.

中文翻译：

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时间平均田鼠将密度与长期栖息地质量相匹配

一个最佳的栖息地选择生物应该使用一种分散策略，使栖息地的占领产生最大的适应度。当栖息地质量随时间变化时，该策略很复杂。理论预测，个体的长期分布将匹配平均栖息地质量，但低于当前的栖息地质量。我通过对占据两对田间围栏的受控田鼠种群进行的实验来测试预测。我在每个围栏内释放了相同数量和相同性别的田鼠，并通过补充喂养来改变围栏之间的资源丰富度。我用人工觅食斑块中的放弃密度 (GUD) 和实验结束时的活诱捕来测量田鼠的反应。数据仅与四个先验扩散模型中的一个一致。放弃密度随着资源供应而下降，因为短期供应对人口密度没有影响。GUD 对实验的时间进程是不变的，因为密度与每个围栏的长期平均质量成正比。实验期间出生的幼年田鼠的性别比例和栖息地占据模式的类似模式加强了对时间平均栖息地匹配的解释。这项研究增加了空间使用策略趋向于行为和进化最优的累积证据。实验期间出生的幼年田鼠的性别比例和栖息地占据模式的相似模式加强了对时间平均栖息地匹配的解释。这项研究增加了空间使用策略趋向于行为和进化最优的累积证据。实验期间出生的幼年田鼠的性别比例和栖息地占据模式的相似模式加强了对时间平均栖息地匹配的解释。这项研究增加了空间使用策略趋向于行为和进化最优的累积证据。