Abstract Context Feral cats (Felis catus) are a significant threat to wildlife in Australia and globally. In Australia, densities of feral cats vary across the continent and also between the mainland and offshore islands. Densities on small islands may be at least an order of magnitude higher than those in adjacent mainland areas. To provide cat-free havens for biodiversity, cat-control and eradication programs are increasingly occurring on Australian offshore islands. However, planning such eradications is difficult, particularly on large islands where cat densities could vary considerably. Aims In the present study, we examined how feral cat densities vary among three habitats on Kangaroo Island, a large Australian offshore island for which feral cat eradication is planned. Methods Densities were compared among the following three broad habitat types: forest, forest–farmland boundaries and farmland. To detect cats, three remote-camera arrays were deployed in each habitat type, and density around each array was calculated using a spatially explicit capture–recapture framework. Key results The average feral cat density on Kangaroo Island (0.37 cats km−2) was slightly higher than that on the Australian mainland. Densities varied from 0.06 to 3.27 cats km−2 and were inconsistent within broad habitat types. Densities were highest on farms that had a high availability of macropod and sheep carcasses. The relationship between cat density and the proportion of cleared land in the surrounding area was weak. The total feral cat population of Kangaroo Island was estimated at 1629 ± 661 (mean ± s.e.) individuals. Conclusions Cat densities on Kangaroo Island are highly variable and may be locally affected by factors such as prey and carrion availability. Implications For cat eradication to be successful, resources must be sufficient to control at least the average cat density (0.37 cats km−2), with additional effort around areas of high carcass availability (where cats are likely to be at a higher density) potentially also being required.

中文翻译：

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南澳大利亚袋鼠岛野猫密度和种群规模的根除前评估

摘要背景野猫（Felis catus）是澳大利亚和全球野生动物的重大威胁。在澳大利亚，野猫的密度在整个大陆以及大陆和近海岛屿之间有所不同。小岛上的密度可能至少比邻近大陆地区的密度高一个数量级。为了为生物多样性提供无猫的庇护所，澳大利亚近海岛屿上越来越多地开展了猫控制和根除计划。然而，计划这样的根除是很困难的，特别是在猫密度可能有很大差异的大岛上。目标 在本研究中，我们研究了袋鼠岛上三个栖息地的野猫密度如何变化，袋鼠岛是一个计划根除野猫的澳大利亚大型近海岛屿。方法 比较了以下三种广泛的栖息地类型的密度：森林、林-农地边界和农田。为了检测猫，每个栖息地类型都部署了三个远程摄像头阵列，每个阵列周围的密度使用空间明确的捕获 - 重新捕获框架计算。主要结果袋鼠岛的平均野猫密度（0.37 只猫 km−2）略高于澳大利亚大陆。密度从 0.06 到 3.27 只猫 km−2 不等，并且在广泛的栖息地类型中不一致。巨足类动物和绵羊尸体供应量高的农场的密度最高。猫密度与周边地区已开垦土地比例之间的关系较弱。袋鼠岛的野猫总数估计为 1629±661（平均值±se）个体。结论袋鼠岛上的猫密度变化很大，可能会受到当地猎物和腐肉供应等因素的影响。影响 为了成功消灭猫，资源必须足以控制至少平均猫密度（0.37 只猫 km-2），并在高可用尸体区域（猫可能处于更高密度的地方）附近进行额外的努力也被要求。