Invasive alien species (IAS) are the major cause of native species extinctions on islands worldwide. To mitigate or eliminate IAS impacts, eradication is often the best alternative. However, IAS removal may result in cascading effects, through increase in prey abundance, mesopredator release, or competitor release. Our objective is to determine which ecological processes may influence the relative abundance of invasive carnivores and rodents on an insular system. We find that feral cat and mustelids relative abundance was strongly related by prey abundance, and for the feral cat, abundance was also controlled by habitat; these results suggest that bottom-up control through environmental filtering could be the mechanism explaining predator abundance. For rodents, we find that the abundance of the black rat was mostly controlled by the abundance of Norway rat and house mice, and food availability; the Norway rat by the abundance of black rat, a house mice and of mustelid predators; and house mouse by the other rodents and food availability. These results suggest that several mechanisms could be concurrently controlling abundance of these species; competition and predation for Norway rat, and competition and bottom-up control by environmental filtering for the other two rodents. While different factors explain the abundance of invasive species within the same functional group, food resource availability is, in general, the main controller of abundance of invasive rodents and carnivores in the Azores. Therefore, IAS management actions in these islands should focus on limiting the access to food resources and shelter, mainly near to human populations.

外来入侵物种 (IAS) 是全球岛屿上本土物种灭绝的主要原因。为了减轻或消除 IAS 的影响，根除通常是最好的选择。然而，通过增加猎物丰度、中掠食性动物释放或竞争者释放，IAS 去除可能会导致级联效应。我们的目标是确定哪些生态过程可能会影响岛屿系统上侵入性食肉动物和啮齿动物的相对丰度。我们发现野猫和鼬科动物的相对丰度与猎物丰度密切相关，而对于野猫来说，丰度也受栖息地控制；这些结果表明，通过环境过滤自下而上的控制可能是解释捕食者丰度的机制。对于啮齿动物，我们发现黑鼠的数量主要受挪威鼠和家鼠的数量以及食物供应情况的控制；黑鼠、家鼠和鲭属食肉动物的丰富性使挪威鼠 和家鼠受到其他啮齿动物和食物供应的影响。这些结果表明，有几种机制可以同时控制这些物种的丰度；挪威鼠的竞争和捕食，以及其他两种啮齿动物的竞争和通过环境过滤的自下而上控制。虽然不同因素解释了同一功能组内入侵物种的丰富程度，但食物资源的可用性通常是亚速尔群岛入侵啮齿动物和食肉动物数量的主要控制者。所以，