Leaver Lisa A, Daly Martin
School of Psychology, University of Exeter, Washington Singer Laboratories, University of Exeter, EX4 4QG, Exeter, UK.
Department of Psychology, McMaster University, Hamilton, Ontario, Canada.
Oecologia. 2001 Aug;128(4):577-584. doi: 10.1007/s004420100686. Epub 2001 Aug 1.
Ecologists studying sympatric heteromyid rodents have sought evidence for species differences in primary foraging abilities and preferences and/or behavioural responses to predation risk in order to explain coexistence. The present field study was conducted to test the hypothesis that another factor may be involved, namely differences in caching patterns, which may result in differences in vulnerability to pilferage. We examined differences between kangaroo rats (Dipodomys merriami) and pocket mice (Chaetodipus spp.) in foraging, caching and pilferage behaviour. Specifically, we examined interactions at food patches, differential food caching patterns, and differential vulnerability to cache pilferage. Observations conducted at artificial seed patches showed that kangaroo rats dominated access to the patches by arriving and foraging first and by chasing pocket mice away. Individually provisioned pocket mice stored most seeds in underground burrows (larder hoarding), whereas kangaroo rats predominantly cached seeds in small, spatially dispersed caches in shallow pits in the surface of the sand (scatter hoarding). Pocket mice pilfered from each other as well as from the kangaroo rats, but the kangaroo rats rarely pilfered, and the only instance was from another kangaroo rat. Kangaroo rats and pocket mice were both vulnerable to cache pilferage. The results suggest that coexistence of kangaroo rats and pocket mice may be facilitated by a trade-off between primary harvest ability and the ability to exploit a resource that has been processed by another species, namely pilferage ability.
研究同域分布的异鼠科啮齿动物的生态学家们一直在寻找证据，以证明物种在主要觅食能力和偏好以及/或者对捕食风险的行为反应方面存在差异，从而解释它们的共存现象。本实地研究旨在检验另一个可能涉及的因素的假设，即贮藏模式的差异，这可能导致被盗取的易感性存在差异。我们研究了更格卢鼠（美利更格卢鼠）和囊鼠（刚毛囊鼠属物种）在觅食、贮藏和被盗取行为方面的差异。具体而言，我们研究了在食物斑块处的相互作用、不同的食物贮藏模式以及贮藏被盗取的不同易感性。在人工种子斑块处进行的观察表明，更格卢鼠通过首先到达并觅食以及将囊鼠赶走，从而主导了对斑块的获取。单独投放食物的囊鼠将大多数种子贮藏在地下洞穴中（集中贮藏），而更格卢鼠则主要将种子分散贮藏在沙地表面浅坑中的小型、空间分散的贮藏点中（分散贮藏）。囊鼠会相互盗取以及从更格卢鼠那里盗取，但更格卢鼠很少盗取，唯一的一次是从另一只更格卢鼠那里盗取。更格卢鼠和囊鼠都容易遭受贮藏被盗取。结果表明，更格卢鼠和囊鼠的共存可能是由于主要收获能力与利用另一个物种处理过的资源的能力（即盗取能力）之间的权衡而得以促进的。
