Dittel Jacob W, Vander Wall Stephen B
Department of Fisheries and Wildlife, Oregon State University, Corvallis, Oregon, USA.
Department of Biology and the Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA.
Integr Zool. 2018 May;13(3):331-338. doi: 10.1111/1749-4877.12317.
Scatterhoarding is a common behavioral strategy to conserve food during periods of scarcity, but this type of food storage is vulnerable to theft or pilferage. A variety of environmental factors and cache characteristics influence the rate of pilferage. Here we investigate 2 environmental factors, which heretofore have not received much attention: the abundance and species richness of scatterhoarding animals in the vicinity of scatterhoarded seeds. We measured the rate of cache pilferage at 7 sites that differed in the number and species composition of granivorous rodents in western Nevada using local native seeds and sunflower seeds. We found that there was no difference between the pilferage rate of native seeds and sunflower seeds, but that sites with different rodent abundances had different pilferage rates. Pilferage rates were proportional to the abundance of scatterhoarding rodents. Scatterhoarding rodents removed seeds at the rate of 1.3%/day/rodent individual. Species richness of scatterhoarding rodents was not correlated with rates of pilferage. These results suggest that density-dependent competition for scatterhoarded seeds is a strong determinant of pilferage rates.
分散贮藏是在食物短缺时期保存食物的一种常见行为策略，但这种食物储存方式容易被盗。多种环境因素和贮藏特征会影响被盗率。在这里，我们研究了两个迄今未受到太多关注的环境因素：分散贮藏种子附近分散贮藏动物的数量和物种丰富度。我们在内华达州西部使用当地原生种子和向日葵种子，在7个地点测量了贮藏被盗率，这些地点的食谷啮齿动物数量和物种组成有所不同。我们发现原生种子和向日葵种子的被盗率没有差异，但啮齿动物数量不同的地点有不同的被盗率。被盗率与分散贮藏啮齿动物的数量成正比。分散贮藏的啮齿动物以每天每只个体1.3%的速度移除种子。分散贮藏啮齿动物的物种丰富度与被盗率无关。这些结果表明，对分散贮藏种子的密度依赖性竞争是被盗率的一个重要决定因素。
