Movements and hunting activity of house cats (Felis catus) living around Travis Wetland, Christchurch, New Zealand

Abstract

The Christchurch City Council is typical of local authorities in New Zealand concerned about the potential impact of house cat populations on conservation areas in urban environments. This thesis estimated the house cat population around Travis Wetland by a door knock survey in January-February 2000. Prey selection of 88 of these cats was then assessed by having owners record the prey their cats retrieved over a 12-month period during November 1999-March 2001. The movements of 21 of the cats was monitored by radio telemetry from May 2000-March 2001.

The estimated population of house cats in a 196ha area of suburban housing around Travis Wetland was 494 cats, of which 170-260 may be visiting the wetland. Of the 21 cats radio tracked from this population, eleven (52%) are known to have visited the wetland. Cats living close to the wetland were more likely to visit the wetland than cats living further away.

Nine hundred and eighty one retrieved prey items were recorded by the cats' owners. These comprised 38% rodents, 19% exotic birds, 18% native skinks, 16% native insects, 6% exotic insects, 1 % native birds and 2% other species such as frogs, goldfish and stoats. Predation appeared to be opportunistic and seasonal, with cats switching prey when availability changed. The mean number of prey items retrieved per cat per year was 11.5 ± 3.0 (SE). The number and type of prey retrieved was not significantly influenced by whether a cat was wearing a collar with a bell, cat gender, cat breed nor the number of times a cat was fed a day. Hunting activity was significantly affected by the age a cat was desexed, cat age and type of food fed to the cat. Cats that lived closer, travelled further and spent more time in the wetland were found to retrieve a greater diversity and number of prey, suggesting that the proximity of natural habitat had a significant influence on the hunting behaviour of these cats. Home range sizes of the radio tracked cats (12 male, 9 female, all desexed) varied from 0.1ha-10.1ha. The maximum distance the cats moved from their homes varied from 29m- 276m. Home ranges of cats living adjacent to the wetland tended to be skewed towards the wetland, which suggests that they were being attracted to it by prey availability. Cats mainly used the periphery of the wetland with the largest recorded movement into the wetland being 198m. Cat age, weather, distance of the cat's home to the wetland periphery and time of the day all influenced the movement of these cats.

In comparison with a similar Australian study where the density of the surrounding house cat population was nearly three times less, the home ranges and movements of house cats in this study were small, which supports the theory that cats living in high density populations tend to restrict their movements.

Further research is required to accurately quantify the impact of house cat predation and the maximum distance that house cats will travel from suburbs to natural adjacent habitat in New Zealand.