Pech R P, Sinclair A R E, Newsome A E, Catling P C
Division of Wildlife and Ecology, CSIRO, PO Box 84, 2602, Lyneham, ACT, Australia.
The Ecology Group, Department of Zoology, University of British Columbia, V6T 1Z4, Vancouver, Canada.
Oecologia. 1992 Jan;89(1):102-112. doi: 10.1007/BF00319021.
Predator-prey studies in semi-arid eastern Australia demonstrated that populations of rabbits (Oryctolagus cuniculus) could be regulated by predators. The functional, numerical and total responses of foxes (Vulpes vulpes) to rabbits and the numerical response of feral cats (Felis catus) to rabbits, are described. Measurement of the rabbit component of foxes' stomach contents indicates a Type III functional response. The size of the fox population in summer was dependent on the availability of rabbits over the immediately preceding rabbit breeding season but there appeared to be no density-dependent aggregation of young foxes in areas of surplus food. The total response of foxes, estimated using the short-term numerical response of dispersing foxes, was directly density-dependent for low rabbit densities and inversely density-dependent for high rabbit densities. Two states are possible with this form of total response: a state with low rabbit densities regulated by predators and a state with high rabbit densities which occurs when rabbits escape predator regulation. The boundary between regulation and non-regulation by predators was demonstrated by a predator-removal experiment. In the treated areas, predators were initially culled and rabbits increased to higher densities than in an untreated area where predators were always present. When predators were allowed back into the treated areas, rabbit populations continued to increase and did not decline to the density in the untreated area. This is the critical evidence for a two-state system. When predators were present, rabbits could be maintained at low densities which were in the density-dependent part of the total response curve for foxes. Exceptionally high rabbit recruitment, or artificially reduced predation, could result in rabbits escaping predator-regulation. Under these circumstances, rabbits could move into the inversely density-dependent region of the total response curve for foxes.
在澳大利亚东部半干旱地区开展的捕食者 - 猎物研究表明，兔子（穴兔）种群数量可受到捕食者的调控。文中描述了狐狸（赤狐）对兔子的功能反应、数量反应和总反应，以及野猫（家猫）对兔子的数量反应。对狐狸胃内容物中兔子成分的测量表明其具有Ⅲ型功能反应。夏季狐狸种群数量的大小取决于紧接其上的兔子繁殖季节兔子的可获得量，但在食物过剩地区，幼狐似乎不存在密度依赖性聚集现象。利用扩散狐狸的短期数量反应估算得出，狐狸的总反应在兔子密度较低时呈直接密度依赖性，在兔子密度较高时呈反向密度依赖性。这种总反应形式可能存在两种状态：一种是兔子密度较低且受捕食者调控的状态，另一种是兔子逃脱捕食者调控时出现的兔子密度较高的状态。捕食者移除实验证明了捕食者调控与非调控之间的界限。在处理区域，最初捕杀了捕食者，兔子数量增加到比始终有捕食者存在的未处理区域更高的密度。当允许捕食者回到处理区域时，兔子种群数量继续增加，并未降至未处理区域的密度。这是双态系统的关键证据。当有捕食者存在时，兔子数量可维持在低密度水平，这处于狐狸总反应曲线的密度依赖性部分。兔子异常高的繁殖率，或人为降低捕食压力，可能导致兔子逃脱捕食者的调控。在这种情况下，兔子可能进入狐狸总反应曲线的反向密度依赖性区域。
