Empresa de Gestión Medioambiental-Consejería de Medio Ambiente, Junta de Andalucía, Granada, Spain.
Oecologia. 2012 Mar;168(3):679-89. doi: 10.1007/s00442-011-2134-6. Epub 2011 Sep 25.
How predators impact on prey population dynamics is still an unsolved issue for most wild predator-prey communities. When considering vertebrates, important concerns constrain a comprehensive understanding of the functioning of predator-prey relationships worldwide; e.g. studies simultaneously quantifying 'functional' and 'numerical responses' (i.e., the 'total response') are rare. The functional, the numerical, and the resulting total response (i.e., how the predator per capita intake, the population of predators and the total of prey eaten by the total predators vary with prey densities) are fundamental as they reveal the predator's ability to regulate prey population dynamics. Here, we used a multi-spatio-temporal scale approach to simultaneously explore the functional and numerical responses of a territorial predator (Bonelli's eagle Hieraaetus fasciatus) to its two main prey species (the rabbit Oryctolagus cuniculus and the red-legged partridge Alectoris rufa) during the breeding period in a Mediterranean system of south Spain. Bonelli's eagle responded functionally, but not numerically, to rabbit/partridge density changes. Type II, non-regulatory, functional responses (typical of specialist predators) offered the best fitting models for both prey. In the absence of a numerical response, Bonelli's eagle role as a regulating factor of rabbit and partridge populations seems to be weak in our study area. Simple (prey density-dependent) functional response models may well describe the short-term variation in a territorial predator's consumption rate in complex ecosystems.
对于大多数野生捕食者-猎物群落而言，捕食者如何影响猎物种群动态仍然是一个悬而未决的问题。在考虑脊椎动物时，一些重要的关注点限制了我们对全球范围内捕食者-猎物关系功能的全面理解；例如，同时量化“功能”和“数量”响应（即“总响应”）的研究很少。功能响应、数量响应和总响应（即捕食者每头猎物的摄入量、捕食者种群和总捕食者吃掉的猎物总量如何随猎物密度变化）是基本的，因为它们揭示了捕食者调节猎物种群动态的能力。在这里，我们使用多时空尺度方法，同时探索了在西班牙南部地中海系统中，繁殖期领地性捕食者（赤肩鹰 Hieraaetus fasciatus）对其两种主要猎物（兔 Oryctolagus cuniculus 和红腿鹧鸪 Alectoris rufa）的功能和数量响应。赤肩鹰对兔/鹧鸪密度变化有功能响应，但没有数量响应。对两种猎物来说，II 型、非调节性的功能响应（典型的特化捕食者）提供了最佳拟合模型。在没有数量响应的情况下，赤肩鹰作为兔和鹧鸪种群调节因子的作用在我们的研究区域似乎较弱。简单的（猎物密度依赖的）功能响应模型可能很好地描述了在复杂生态系统中领地性捕食者消费率的短期变化。
