Abstract Context. Introduced predators, especially cats, are a major cause of extinction globally. Accordingly, an extensive body of literature has focussed on the ecology and management of feral cats in continental and island systems alike. However, geographic and climatic gaps remain, with few studies focusing on rainforests or tropical islands of the south-western Pacific. Aims. We aimed to estimate cat densities and elucidate activity patterns of cats and sympatric birds and mammals in tropical island rainforests. We hypothesised that cat activity would be most influenced by the activity of introduced rodents and ground-dwelling birds that are predominant prey on islands. Methods. We used camera traps to detect feral cats, pigs, rodents and birds on four tropical islands in the south-western Pacific. We used spatial capture–recapture models to estimate the abundance and density of feral cats. Relative abundance indices, and temporal overlaps in activity were calculated for feral cats, pigs, rodents, and birds. We used a generalised linear model to test for the influence of pig, rodent, and bird abundance on feral cat abundance. Key results. The species most commonly detected by our camera traps was feral cat, with estimated densities between 0.31 and 2.65 individuals km−2. Pigs and introduced rodents were the second- and third-most commonly detected fauna respectively. Cat activity was bimodal, with peaks in the hours before dawn and after dusk. Cat abundance varied with site and the abundance of rodents. Conclusions. Feral cats are abundant in the tropical rainforests of our study islands, where one bird and two mammal species are now presumed extinct. Introduced rodents possibly amplify the abundance and impacts of feral cats at our sites. Peak cat activity following dusk did not clearly overlap with other species detected by our camera traps. We postulate cats may be partly focussed on hunting frogs during this period. Implications. Cats are likely to be a major threat to the highly endemic fauna of our study region. Management of feral cats will benefit from further consideration of introduced prey such as rodents, and their role in hyperpredation. Island archipelagos offer suitable opportunities to experimentally test predator–prey dynamics involving feral cats.

中文翻译：

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热带岛屿雨林中野猫的数量、密度和活动

摘要上下文。引入的捕食者，尤其是猫，是全球灭绝的主要原因。因此，大量文献都集中在大陆和岛屿系统中野猫的生态学和管理上。然而，地理和气候差距仍然存在，很少有研究关注西南太平洋的热带雨林或热带岛屿。目标。我们旨在估计猫的密度并阐明热带岛屿雨林中猫和同域鸟类和哺乳动物的活动模式。我们假设猫的活动受引入的啮齿动物和陆栖鸟类活动的影响最大，这些鸟类是岛屿上的主要猎物。方法。我们使用相机陷阱检测西南太平洋四个热带岛屿上的野猫、猪、啮齿动物和鸟类。我们使用空间捕获-重新捕获模型来估计野猫的数量和密度。计算了野猫、猪、啮齿动物和鸟类的相对丰度指数和活动的时间重叠。我们使用广义线性模型来测试猪、啮​​齿动物和鸟类丰度对野猫丰度的影响。关键结果。我们的相机陷阱最常检测到的物种是野猫，估计密度在 0.31 到 2.65 只个体 km−2 之间。猪和引入的啮齿动物分别是第二和第三大最常检测到的动物群。猫的活动是双峰的，在黎明前和黄昏后的几个小时达到高峰。猫的数量因地点和啮齿动物的数量而异。结论。在我们研究岛屿的热带雨林中，野猫很丰富，一种鸟类和两种哺乳动物现在被推定灭绝。引入的啮齿动物可能会放大我们所在地野猫的数量和影响。黄昏后的峰值猫活动与我们的相机陷阱检测到的其他物种没有明显重叠。我们假设在此期间猫可能部分地专注于捕猎青蛙。影响。猫很可能是我们研究地区高度地方性动物群的主要威胁。对野猫的管理将受益于进一步考虑引入的猎物（如啮齿动物）及其在过度捕食中的作用。岛屿群岛提供了合适的机会来实验测试涉及野猫的捕食者-猎物动态。黄昏后的峰值猫活动与我们的相机陷阱检测到的其他物种没有明显重叠。我们假设在此期间猫可能部分地专注于捕猎青蛙。影响。猫很可能是我们研究地区高度地方性动物群的主要威胁。对野猫的管理将受益于进一步考虑引入的猎物（如啮齿动物）及其在过度捕食中的作用。岛屿群岛提供了合适的机会来实验测试涉及野猫的捕食者-猎物动态。黄昏后的峰值猫活动与我们的相机陷阱检测到的其他物种没有明显重叠。我们假设在此期间猫可能部分地专注于捕猎青蛙。影响。猫很可能是我们研究地区高度地方性动物群的主要威胁。对野猫的管理将受益于进一步考虑引入的猎物（如啮齿动物）及其在过度捕食中的作用。岛屿群岛提供了合适的机会来实验测试涉及野猫的捕食者-猎物动态。以及它们在过度捕食中的作用。岛屿群岛提供了合适的机会来实验测试涉及野猫的捕食者-猎物动态。以及它们在过度捕食中的作用。岛屿群岛提供了合适的机会来实验测试涉及野猫的捕食者-猎物动态。