RPG: Tactical Defensibility: Landmarks and Territorial Behavior

[9707464]原因许多动物都是有领地意识的，个体保护自己的区域不受同种动物的侵害。领土所有者在保卫领土的过程中付出了成本，但也从领土的资源中获益；利益必须大于成本，防御才是可行的。以前的工作忽略了领土的一个特征，这个特征可能对决定其所有者的成本至关重要：战术防御能力，或防御特定地点的相对难度。一个可能是防御能力的主要决定因素是栖息地中地标的存在与否。来自各种各样的分类群（昆虫、鱼类、爬行动物、鸟类和哺乳动物）的轶事报告表明，动物使用自然发生的和人为的特征作为领土边界。这一普遍现象很少受到科学家的关注，本研究将解决这一失误。研究的系统是蝉杀蜂（Sphecius speciosus）的领土行为。这个物种的雄性在平坦无特征的地面上保卫交配领地。这一物种对地标反应强烈：雄黄蜂会移动他们的领土，使边界与地标一致，如果提供的地标，如销钉。这项研究将确定通过引入地标来操纵领土大小和形状的程度。在实验中，网格将由销子构成，网格中单元的大小和形状将是不同的。行为数据也将被收集。获得的数据将用于检验战术防御对蝉杀手的防御成本和雄性交配成功率的影响。研究结果将提供生境异质性对领地大小的影响，从而对雄性密度的影响。这些数据对理论生态学家很有价值，而且对保护生物学家也有实际用途：了解栖息地异质性如何影响领土物种，可以使野生生物学家创造更适合受威胁物种或经济上重要物种的栖息地。

9707464 Eason Many animal species are territorial, with individuals defending areas against conspecifics. Territory owners incur costs from defending the territory, but also benefits from the territory's resources; benefits must outweigh costs for defense to be feasible. Previous work has ignored a characteristic of territories that may be critical in determining the costs of their owners: tactical defensibility, or the relative difficulty of defending a particular site. One factor that may be the primary determinant of defensibility is the presence or absence of landmarks in the habitat. Anecdotal reports from a wide variety of taxa (insects, fish, reptiles, birds, and mammals) have suggested that animals use naturally occurring and man-made features as territorial boundaries. This common phenomenon has received very little attention from scientists, and this study will address this lapse. The system to be studied is the territorial behavior of the cicada killer wasp (Sphecius speciosus). Males of this species defend mating territories on flat, featureless ground. This species responds strongly to landmarks: male wasps will move their territories so that the boundaries coincide with landmarks, if landmarks such as dowels are provided. This study will determine the degree to which the size and shape of territories can be manipulated by introducing landmarks. For experiments, grids will be constructed of dowels, and the size and shape of the units in the grid will be varied. Behavioral data will also be collected. The data obtained will be used to examine the effects of tactical defensibility on defensive costs and male mating success in cicada killers. The results will provide information about the effects of habitat heterogeneity on territory size and thus on the density of males. Such data are of value to theoretical ecologists and in addition will be of practical use to conservation biologists: an understanding of how habitat heteroge neity affects territorial species may enable wildlife biologists to create habitats that are more suitable to threatened or economically important species.