RAMHSS: Effects of Bird Predation and Interspecific Competition on Grasshoppers: A Field Experimental Study

捕食和种间竞争可以相互作用来决定物种的分布和丰度，但这种相互作用在陆地生态系统中很少被实验研究。指甲虫是亚利桑那州东南部草原上数量丰富的蝗虫。它的颜色也很艳丽，明显令人反感，而且对鸟类的捕食免疫。拟议研究区内其他常见的蝗虫是繁殖鸟类的主要猎物。它们还可能与指甲争夺食物和栖息地。初步数据表明，鸟类可以对蝗虫种群产生重大影响，指甲虫种群可以在野外得到有效控制。在亚利桑那州东南部的草原保护区复制的地块将被用来排除鸟类，或2)指藻，或3)两者，或4)两者都不。从7月到10月，将在治理前的一年和治理后的三年内测量蝗虫密度。结果将检验关于鸟类捕食和种间竞争对这片半荒漠草原蝗虫数量的独立和交互影响的假设。简博士和卡尔·博克博士将共同致力于这些实验。他们出色的研究记录确保了富有成效的努力。

Predation and interspecific competition can interact to determine the distribution and abundance of species, but such interactions rarely have been studied experimentally in terrestrial ecosystems. Dactylotum is an abundant grasshopper in the grasslands of southeastern Arizona. It also is gaudily- colored, apparently distasteful, and immune from predation by birds. Other common grasshoppers in the proposed study area comprise the major prey of breeding birds. They also potentially compete with Dactylotum for food and habitat. Preliminary data indicate that birds can have a significant impact on grasshopper populations, and that Dactylotum populations can be manipulated effectively in the field. Replicated plots on a grassland preserve in southeastern Arizona will be used to exclude 1) birds, or 2) Dactylotum, or 3) both, or 4) neither. Grasshopper densities will be measured on the plots from July to October for one pre-treatment and three post-treatment years. Results will test hypotheses about the independent and interactive effects of bird predation vs. interspecific competition upon the abundances of grasshoppers in this semidesert grassland. Drs. Jane and Carl Bock will work jointly on these experiments. Their excellent research records assure a productive endeavor.