Molsher Robyn, Newsome Alan E, Newsome Thomas M, Dickman Christopher R
Department of Environment, Water and Natural Resources, Kangaroo Island, South Australia, Australia.
CSIRO, Lyneham, Canberra, Australian Capital Territory, Australia.
PLoS One. 2017 Jan 9;12(1):e0168460. doi: 10.1371/journal.pone.0168460. eCollection 2017.
Apex predators are subject to lethal control in many parts of the world to minimize their impacts on human industries and livelihoods. Diverse communities of smaller predators-mesopredators-often remain after apex predator removal. Despite concern that these mesopredators may be 'released' in the absence of the apex predator and exert negative effects on each other and on co-occurring prey, these interactions have been little studied. Here, we investigate the potential effects of competition and intraguild predation between red foxes (Vulpes vulpes) and feral cats (Felis catus) in south-eastern Australia where the apex predator, the dingo (Canis dingo), has been extirpated by humans. We predicted that the larger fox would dominate the cat in encounters, and used a fox-removal experiment to assess whether foxes affect cat abundance, diet, home-range and habitat use. Our results provide little indication that intraguild predation occurred or that cats responded numerically to the fox removal, but suggest that the fox affects some aspects of cat resource use. In particular, where foxes were removed cats increased their consumption of invertebrates and carrion, decreased their home range size and foraged more in open habitats. Fox control takes place over large areas of Australia to protect threatened native species and agricultural interests. Our results suggest that fox control programmes could lead to changes in the way that cats interact with co-occurring prey, and that some prey may become more vulnerable to cat predation in open habitats after foxes have been removed. Moreover, with intensive and more sustained fox control it is possible that cats could respond numerically and alter their behaviour in different ways to those documented herein. Such outcomes need to be considered when estimating the indirect impacts of fox control. We conclude that novel approaches are urgently required to control invasive mesopredators at the same time, especially in areas where apex predators are absent.
在世界许多地区，顶级食肉动物受到致命控制，以尽量减少它们对人类产业和生计的影响。在顶级食肉动物被清除后，往往会留下由各种较小食肉动物组成的多样化群落——中食肉动物。尽管有人担心这些中食肉动物可能会在没有顶级食肉动物的情况下“被释放”，并对彼此以及同时存在的猎物产生负面影响，但对这些相互作用的研究却很少。在此，我们调查了澳大利亚东南部赤狐（赤狐属）和野猫（家猫属）之间竞争和集团内捕食的潜在影响，在该地区，顶级食肉动物澳洲野犬（澳洲野犬属）已被人类灭绝。我们预测体型较大的狐狸在相遇时会占据主导地位，并通过一项去除狐狸的实验来评估狐狸是否会影响猫的数量、饮食、活动范围和栖息地利用。我们的结果几乎没有表明发生了集团内捕食，或者猫在数量上对狐狸的去除有反应，但表明狐狸会影响猫资源利用的某些方面。特别是，在去除狐狸的地方，猫增加了对无脊椎动物和腐肉的消耗，缩小了它们的活动范围，并在开阔栖息地觅食更多。在澳大利亚的大片地区都在进行狐狸控制，以保护受威胁的本土物种和农业利益。我们的结果表明，狐狸控制计划可能会导致猫与同时存在的猎物相互作用方式的改变，并且在狐狸被去除后，一些猎物在开阔栖息地可能更容易受到猫的捕食。此外，随着对狐狸进行更密集和持续的控制，猫有可能在数量上做出反应，并以与本文记录的不同方式改变它们的行为。在估计狐狸控制的间接影响时，需要考虑这些结果。我们得出结论，迫切需要新的方法来同时控制入侵的中食肉动物，特别是在没有顶级食肉动物的地区。
