Jaksié F M, Jiménez J E, Castro S A, Feinsinger P
Departamento de Ecología, Universidad Católica de Chile, Casilla 114-D, Santiago, Chile.
Department of Wildlife and Range Sciences, University of Florida, 32611, Gainesville, FL, USA.
Oecologia. 1992 Jan;89(1):90-101. doi: 10.1007/BF00319020.
Occurrence and diet of ten carnivorous predators (four falconiforms, four owls, and two foxes), and population levels of their mammalian prey, were monitored over 45 months at a semi-arid site in north-central Chile. Early in this period, small mammals irrupted and then declined markedly to a density 7% of that at peak. All four falconiforms (Buteo polyosoma, Falco sparverius, Geranoaetus melanoleucus, Parabuteo unicinctus) and one owl (Tyto alba) responded numerically to the decline in mammalian prey by virtually abandoning the study site. The three other owls (Athene cunicularia, Bubo virginianus, Glaucidium nanum) and the two foxes (Pseudalopex culpaeus and P. griseus) remained. With few exceptions, throughout the study predators maintained species-specific preferences among small mammal species regardless of the absolute and proportional abundance of these prev. At no time did the two prey species most responsible for the irruption (the rodents Phyllotis darwini and Akodon olivaceus) occur in predators' diets out of proportion to their estimated relative abundance in the field. Predators were clearly unable to prevent the irruption from occurring. Given the absence of a clear functional response to the most irruptive species, predators seemed unlikely to have been responsible for the observed crash. At present, however, predators may be prolonging the crash and delaying the return of small-mammal populations to typical densities.
在智利中北部的一个半干旱地区，对10种食肉动物（4种隼形目、4种猫头鹰和2种狐狸）的出现情况、饮食以及它们的哺乳动物猎物的种群数量进行了为期45个月的监测。在此期间早期，小型哺乳动物数量激增，随后显著下降至峰值密度的7%。所有4种隼形目动物（棕尾鵟、美洲隼、黑领鹰、条纹鹰）和1种猫头鹰（仓鸮）实际上放弃了研究地点，在数量上对哺乳动物猎物数量的下降做出了反应。另外3种猫头鹰（穴小鸮、大角鸮、侏鸺）和2种狐狸（草原狐和灰狐）留了下来。除了少数例外情况，在整个研究过程中，无论这些猎物的绝对数量和相对比例如何，食肉动物在小型哺乳动物物种之间都保持着特定物种的偏好。引发数量激增的两种猎物物种（达尔文叶耳鼠和橄榄色稻鼠）在食肉动物的饮食中从未与其在野外估计的相对丰度不成比例地出现过。食肉动物显然无法阻止数量激增的发生。鉴于对数量激增最明显的物种没有明显的功能反应，食肉动物似乎不太可能是导致观察到的数量崩溃的原因。然而目前，食肉动物可能正在延长数量崩溃的时间，并延迟小型哺乳动物种群恢复到典型密度。
