RUI: Incidental Nest Predation in Songbirds: Using Behavioral Indicators to Determine Ecological Processes and Scales

0089588. 肯尼斯·施密特。捕食率和捕食者对猎物的后续影响被认为主要是由捕食者的种群密度决定的。尽管如此，通才型捕食者在寻找主要猎物时碰巧遇到次要猎物类型时，可能会进行许多捕食。这种偶然捕食是由单个捕食者对可选择的猎物种类的丰富度和分布以及捕食者环境特征的行为反应决定的。偶然捕食在通才捕食者中极为常见，而在专才捕食者中则较少。由于这种弱相互作用可能稳定群落结构，因此它们相当重要。更具体地说，偶然捕食的比率可能与敌人自由空间（未被捕食者利用的区域）的数量有关。了解这一机制至关重要，因为它与捕食者-猎物相互作用的强度有关，也因为无敌人空间影响捕食者-猎物动态的稳定性和多种猎物物种的共存。拟议的研究考察了一个繁殖鸣禽群落的偶然捕食，这些鸣禽的蛋和雏鸟被小型哺乳动物捕食，主要是白足鼠（Peromyscus leucopus）。它侧重于从个体行为和种群动态的角度研究捕食，以及它们对社区现象的影响。该方法结合了理论、观察和实验成分，最终测试明确的潜在机制。更具体地说，研究包括：(1)监测常见脊椎动物（白足鼠、东部花栗鼠、灰松鼠）的密度，这些脊椎动物是鸣禽的巢捕食者；(2)使用人工鸣禽巢穴监测巢捕食率；(3)监测选定鸣禽物种自然筑巢的成功率；(4)测试无敌人空间是否是控制意外捕食的关键因素。(5)在多空间尺度上评价放弃密度作为生态格局和过程指标的效用；(6)估计种群密度和捕食者个体行为反应对鸣禽巢生存的影响。

0089588. Kenneth Schmidt. Predation rates and the subsequent impact of predators on prey are thought to be determined mostly by the population density of predators. Nonetheless, much predation by generalist predators may occur when secondary prey types are encountered coincidentally by a predator while searching for its primary prey. Such incidental predation is determined by the behavioral responses of individual predators to the abundance and distribution of alternative prey types, as well as to features of the predator's environment. Incidental predation may be extremely common in generalist, and to a smaller degree in specialist predators. Because such weak interactions potentially stabilize community structure, they are of considerable importance. More specifically, the rate of incidental predation may be related to amount of enemy-free space (areas unutilized by predators). Understanding this mechanism is critical because of its relationship to the strength of the predator-prey interaction, as well because enemy-free space influences the stability of predator-prey dynamics and the coexistence of multiple prey species.The proposed research examines incidental predation in a community of breeding songbirds, whose eggs and nestlings are preyed on by small mammals, primarily the white-footed mouse (Peromyscus leucopus). It focuses on predation from the perspectives of individual behaviors and population dynamics, as well as their repercussions to community-level phenomena. The approach combines theoretical, observational, and experimental components, ultimately to test explicit underlying mechanisms. More specifically, the research involves (1) monitoring the density of common vertebrates (white-footed mouse, eastern chipmunk, gray squirrel) which are nest predators of songbirds (2) monitoring nest predation rates using artificial songbird nests, and (3) monitoring the success of natural nests of selected songbird species, (4) testing if enemy-free space is a key control of incidental predation, (5) evaluating the utility of giving-up densities as indicators of ecological patterns and processes at multiple spatial scales, and (6) estimating the influence of population density and individual behavioral responses of predators on the survival of nests of songbirds.