Long-term monitoring reveals the value of continuous trapping to curtail the effects of free-roaming cats in protected island habitats

Abstract

Free-roaming domestic cats (Felis catus) pose numerous risks to biodiversity conservation, especially in island ecosystems. However, the removal of cats is costly, labor-intensive, and often demands more resources than land managers have at their disposal. These costs might be reduced, however, if trapping effort is regularly scaled to match the prevalence of cats on the landscape rather than consistently exhausting trapping resources even when cats are scarce. Here we analyze the efficacy of a long-term (2014 – 2021) cat removal program which uses motion-activated camera traps to determine monthly trapping effort in the Florida Keys. Furthermore, we compare the trapping effort required for this program against that of a hypothetical removal program with the same resources which does not use surveillance-informed trapping. We hypothesized that cat detections would decline over the study period as a result of the removal program, and that the surveillance-informed approach would require less trapping effort than uninformed trapping would. Our analyses reveal that the sustained, year-round trapping program has reduced the volume and geographic extent of cat detections within the study area. Furthermore, the use of camera traps to inform removal efforts has reduced the number of trap nights required to achieve these goals compared to the hypothetical removal program that did not use surveillance-informed trapping. While climatic and landscape variables also contribute to monthly cat detections, our study reveals that long-term surveillance-informed trapping reduces cat detections without exhausting resources. Such an approach may aid other land managers in their efforts to conserve biodiversity by removing invasive predators.

Keywords

• Invasive species control
• Camera trap monitoring
• Live-trapping
• Population management
• Florida keys