The movements of 10 house cats (4 desexed females, 5 desexed males and 1 intact male) living on the edge of a suburb adjoining grassland and forest/woodland habitat, and a neighbouring colony of seven farm cats, were examined using radio‐telemetry over nine months Nocturnal home range areas of the suburban cats varied between 0 02 and 27 93 ha (mean 7 89 ha), and were larger than diurnal home range areas (range 0 02 to 17 19 ha – mean 2 73 ha) Nocturnal home range areas of cats from the farm cat colony varied between 1 38 and 4 46 ha (mean 2 54 ha), and were also larger than diurnal home range areas (range 0 77 to 3 70 ha – mean 1 70 ha) Home ranges of cats in the farm cat colony overlapped extensively, as did those of cats living at the same suburban residence There was no overlap of home ranges of female cats from different residences, and little overlap between males and females from different residences Four of the suburban house cats moved between 390 m and 900 m into habitat adjoining the suburb Polygons describing the home ranges of these animals were strongly spatially biased away from the suburban environment, though the cats spent the majority of their time within the bounds of the suburb Movements further than 100–200 m beyond the suburb edge were always made at night There is evidence that home range sizes and spatial movement patterns of house cats are largely determined by a) the density and spatial distribution of cats utilising separate food resources, b) the personality and social dominance of individual cats, c) the location of favoured hunting and resting/sunning sites, and, d) barriers such as busy roads

Studies of predation by house cats in Australia have not attempted to compare the composition of prey taken by cats with the relative availability of prey. Information on the composition of vertebrate prey caught by house cats in Canberra was collected by recording prey deposited at cat owners’ residences over 12 months. A total of 1961 prey representing 67 species were collected or reported. In all, 64% of prey were introduced mammals, especially mice and rats, with birds comprising 27% (14% native, 10% introduced, 3% unidentified), reptiles 7%, amphibians 1% and native mammals 1%. Predatory behaviour by house cats appeared largely opportunistic with respect to spatial (habitat) and temporal (daily and seasonal) prey availability and accessibility, although there is mounting evidence from this and other studies that small mammals are the preferred prey. While this means that introduced mice and rats are common prey of house cats in urban and suburban environments, it also suggests that in relatively undisturbed environments adjoining new residential developments, predation by house cats may have a substantial impact on locally abundant, patchily distributed populations of native fauna, particularly mammals. Imposing night-time curfews on cats is likely to lessen predation of mammals but will probably not greatly reduce predation of birds or reptiles.

Information on the amount of vertebrate prey caught by house cats in Canberra was collected by recording prey deposited at cat owners’ residences over 12 months. The amount of prey taken was not significantly influenced by cat gender, age when neutered, or cat breed. Nor did belling or the number of meals provided per day have a significant influence on the amount of prey caught. The age of the cat and the proportion of nights spent outside explained approximately 11% of the variation in the amount of prey caught by individual cats. In all, 43% of variation in predation on introduced species (predominantly rodents) was explained by distance from potential prey source areas (i.e. rural/grassland habitat) and cat density. The mean number of prey reported per cat over 12 months (10.2) was significantly lower than mean predation per cat per year based on estimates made by cat owners before the prey survey began (23.3). Counts of the amount of prey caught by house cats were highly positively skewed. In all, 70% of cats were observed to catch less than 10 prey over 12 months, but for 6% of cats, more than 50 prey were recorded. Estimates of predation by house cats, particularly extrapolated estimates, should be treated with caution. The total number of prey caught by house cats in Canberra estimated using the sample median was approximately half the estimate based on the sample mean. Predation estimates alone do not prove that prey populations are detrimentally affected, especially in highly disturbed and modified environments such as suburbs. Impacts on native fauna are likely to be most significant in undisturbed habitat adjacent to new residential developments.

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