Behavioral Adaptation to a Desert Environment: An Experimental Comparative Study of Food Hoarding

许多动物在食物充足时储存食物，以备资源匮乏时使用。食物囤积通常有两种类型：将大量食物储存在一个集中的地方，如洞穴（储藏室囤积），以及将许多小的食物分散在个体的家庭范围内（分散囤积）。袋鼠鼠是一种沙漠啮齿动物，它们把囤积食物作为应对沙漠环境不可预测的一种策略。共存的袋鼠鼠囤积食物的方式各不相同：有些种类是囤积型的，有些则主要是分散囤积型的。本研究将使用实验室和实地实验来测试袋鼠大鼠食物囤积模式差异的三个假设。具体来说，因为体型较大的袋鼠鼠对体型较小的袋鼠鼠具有侵略性的统治地位，所以体型较小的动物，如梅里亚姆和奥尔德的袋鼠鼠，应该比体型较大的动物，如Panamint和沙漠袋鼠鼠，更少地囤积种子，更广泛地分散储存，更频繁地移动贮藏物，以应对盗窃。詹金斯博士还将比较来自不同竞争对手的地点的同一物种的不同种群，以验证囤积行为是适应特定种群成员所遇到的竞争环境的预测。这项研究之所以重要，有几个原因。首先，沙漠啮齿动物是研究竞争在生态系统结构和功能中的作用的模型系统。尽管竞争对沙漠啮齿动物的普遍影响已经得到了很好的证实，但调节竞争的具体行为机制却很少受到关注。作为袋鼠大鼠适应沙漠环境的一种关键行为，食物囤积可能与物种间的竞争密切相关。其次，由于理论的发展和理论模型预测的实证检验之间的富有成效的相互作用，最优觅食已成为近年来行为生态学中最富有成果的研究领域之一。作为觅食行为的一个方面，迄今为止对食物囤积的研究主要是描述性的。本实验研究将袋鼠大鼠的食物囤积行为置于最佳觅食生态学的背景下，有助于对食物囤积行为有更广泛的认识。第三，囤积散种动物是许多植物种子传播的重要媒介。这项对导致袋鼠鼠分散囤积与囤积囤积的因素的研究将有助于更好地理解这些动物与沙漠植物种群之间的相互作用，从而有利于沙漠环境的保护。

Many animals store food in times of plenty for use later when resources are scarce. Two general types of food hoarding occur: storing large amounts of food in a centralized location such as a burrow (larder-hoarding), and scattering many small caches of food throughout an individual's home range (scatter-hoarding). Kangaroo rats are desert rodents that use food hoarding as a strategy for dealing with the unpredictability of desert environments. Coexisting kangaroo rats differ in their food- hoarding patterns: some species are larder-hoarders, others are primarily scatter-hoarders. This study will use laboratory and field experiments to test three hypotheses about differences in food-hoarding patterns of kangaroo rats. Specifically, because larger kangaroo rats are aggressively dominant to smaller ones, smaller animals such as Merriam's and Ord's kangaroo rats should larder-hoard fewer seeds, make more widely-spaced scatter-hoards and move caches more often in response to theft than larger animals such as Panamint and desert kangaroo rats. Dr. Jenkins will also compare different populations of the same species from sites with different suites of competitors, to test the prediction that hoarding behavior is adapted to the competitive environment encountered by members of a particular population. This study is important for several reasons. First, desert rodents have been model systems for studies of the role of competition in ecosystem structure and function. Although the pervasive influence of competition among desert rodents has been well established, specific behavioral mechanisms that mediate competition have received little attention. As a key behavioral adaptation of kangaroo rats to desert environments, food hoarding is likely to be closely connected to competition among species. Second, optimal foraging has been one of the most fruitful areas of study in behavioral ecology in recent years because of the productive interplay between development of theory and empirical tests of predictions derived from theoretical models. As an aspect of foraging behavior, work on food hoarding has been mainly descriptive to date. This experimental study of food hoarding by kangaroo rats will contribute to a broader perspective on food hoarding by placing it in the context of optimal foraging ecology. Third, scatter-hoarding animals are important agents of dispersal for the seeds of many plant species. This study of factors that cause kangaroo rats to scatter-hoard vs. larder-hoard will lead to greater understanding of interactions between these animals and desert plant populations, with consequent benefits for conservation of desert environments.