Department of Primary Industries, Parks, Water and Environment, 134 Macquarie Street, Hobart, Tasmania, Australia.
Tasmanian Museum and Art Gallery, Dunn Place, Hobart, Tasmania, Australia.
Ecol Appl. 2021 Sep;31(6):e02362. doi: 10.1002/eap.2362. Epub 2021 Jun 3.
Feral individuals of the cat Felis catus are recognized internationally as a threat to biodiversity. Open, non-insular systems support a large proportion of the world's biodiversity, but the population-level impacts of feral cats in these systems are rarely elucidated. This limits prioritization and assessment of the effectiveness of management interventions. We quantified the predatory impact of feral cats on small mammals in open, non-insular forest systems in Tasmania, Australia in the context of other factors hypothesized to affect small mammal densities and survival, namely the density of a native carnivore, co-occurring small mammals, and rainfall. Change in feral cat density was the most important determinant of small mammal density and survival. We calculated that, on average, a 50% reduction in feral cat density could result in 25% and 10% increases in the density of the swamp rat Rattus lutreolus and long-tailed mouse Pseudomys higginsi, respectively. Low-level culling of feral cats that we conducted on two of our four study sites to experimentally alter feral cat densities revealed that swamp rat survival was highest when feral cat densities were stable. We conclude that feral cats exert downward pressure on populations of indigenous small mammals in temperate forest systems. However, alleviating this downward pressure on prey by culling a large proportion of the feral cat population is difficult as current methods for reducing feral cat populations in cool temperate forest systems are ineffective, and potentially even counterproductive. We suggest using an adaptive approach that regularly and robustly monitors how feral cats and small mammals respond to management interventions that are intended to conserve vulnerable prey species.
猫科动物中的野猫被国际公认为对生物多样性的威胁。开放的、非岛屿系统支持着世界上很大一部分的生物多样性，但这些系统中野猫对小型哺乳动物的种群水平影响很少被阐明。这限制了对管理干预措施的优先排序和评估。我们在澳大利亚塔斯马尼亚的开放、非岛屿森林系统中量化了野猫对小型哺乳动物的捕食影响，同时考虑了其他被假设会影响小型哺乳动物密度和生存的因素，即本地肉食动物的密度、共存的小型哺乳动物和降雨量。野猫密度的变化是影响小型哺乳动物密度和生存的最重要决定因素。我们计算得出，平均而言，野猫密度降低 50%可能会导致沼泽鼠和长尾鼠标本氏鼩的密度分别增加 25%和 10%。我们在四个研究点中的两个点进行了低水平的野猫扑杀，以实验性地改变野猫密度，结果表明，当野猫密度稳定时，沼泽鼠的存活率最高。我们得出结论，野猫对温带森林系统中本土小型哺乳动物的种群施加了下行压力。然而，通过扑杀大部分野猫种群来减轻对猎物的这种下行压力是困难的，因为目前减少凉爽温带森林系统中野猫种群的方法效果不佳，甚至可能适得其反。我们建议采用一种适应性方法，定期和强有力地监测野猫和小型哺乳动物对旨在保护脆弱猎物物种的管理干预措施的反应。
