Distribution and diet of feral cats (Felis catus) in the Wet Tropics of north-eastern Australia, with a focus on the upland rainforest

Context. Feral cats have been identified as a key threat to Australia's biodiversity, particularly in arid areas and tropical woodlands. Their presence, abundance and potential impacts in rainforest have received less attention. Aims. To investigate the distribution and diet of feral cats (Felis catus) in upland rainforest of the Wet Tropics. Methods. We collated available occurrence records from the Wet Tropics, and data from upland camera-trapping surveys over an 8-year period, to assess geographic and elevational distribution of feral cats in the bioregion. We also assessed the diet of feral cats from scats collected at upland sites. Key results. Feral cats are widespread through the Wet Tropics bioregion, from the lowlands to the peaks of the highest mountains (.1600 m), and in all vegetation types. Abundance appears to vary greatly across the region. Cats were readily detected during camera-trap surveys in some upland rainforest areas (particularly in the southern Atherton Tablelands and Bellenden Ker Range), but were never recorded in some areas (Thornton Peak, the upland rainforest of Windsor Tableland and Danbulla National Park) despite numerous repeated camera-trap surveys over the past 8 years at some of these sites. Scat analysis suggested that small mammals comprise similar to 70% of the diet of feral cats at an upland rainforest site. Multivariate analysis could not detect a difference in mammal community at sites where cats were detected or not. Conclusions. Feral cats are widespread in the Wet Tropics and appear to be common in some upland areas. However, their presence and abundance are variable across the region, and the drivers of this variability are not resolved. Small mammals appear to be the primary prey in the rainforest, although the impacts of cats on the endemic and threatened fauna of the Wet Tropics is unknown. Implications. Given their documented impact in some ecosystems, research is required to examine the potential impact of cats on Wet Tropics fauna, particularly the many upland endemic vertebrates. Studies are needed on (1) habitat and prey selection, (2) population dynamics, and (3) landscape source-sink dynamics of feral cats in the Wet Tropics.