Ecology of feral cats, Felis catus L, in an urban parkland environment

The Lane Cove River Valley and its surrounding region is an integral ecological component of the Lane Cove River National Park. It is important for the survival of sustainable populations of several species of mammals including predator species such as feral cats, birds, other vertebrates, and several species of invertebrates. A combination of radio-tracking, visual observation techniques and scat analysis of feral cats was undertaken between December 1995 and April 1997 in this area. This study was conducted in order to provide information on the home ranges, diet and activity of feral cats in an urban environment. In this study, two methods were used to analyse home range areas: minimum convex polygons and the adaptive kernel, utilising 95%, 90%, 60%, and 50% isopleths. Based on the 95% isopleth, it was confirmed that overall mean home range areas were not significantly different between males and females. This could be the result of limited animals studied, limited time spent tracking for two males due to removal by local people or the nature of the surrounding study area such as its specific habitat and food availability. Based on mean monthly distance travelled, however, males showed greater range areas than females. It was also confirmed that differences in distance travelled occurred among two females. On the basis of scat analysis, mainly on the identification of mammalian hair, together with conventional methods of direct observation, feral cat was found to use a wide dietary range. The major food categories in terms of percentage occurrence were mammals (80%), herbage materials (43%), household refuse (22%). Of those 80% containing mammal remains, rabbit was the most common prey item (18%), followed by the ringtail possum (16%), black rat (14%), and southern bushrat and house mouse both comprised (8%). Scat analysis was able to detect the presence of the uncommon or inconspicuous species on two occasion, possibly the water rat. Non-mammalian items for the feral cat were birds (18%), insects (28%), other vertebrates (2%). Finally, feral cats in this study were nocturnal although several daily movements were recorded. The percentage of time used varied with individual and hour of the night. Activity was mostly bimodal with peaks occurring between 20.00h and 23.00h and at early morning. Activity levels for males was greater in late summer while females showed increased activity in winter.