Austaralian Study Finds Cat Predation Not Significant

Dr Lilith found no evidence that pet cats had slashed the population of small mammals. Species diversity and abundance was virtually identical from subdivision to subdivision.

Cat among conservationist pigeons

Cat among conservationist pigeons
Armadale city staff plan to do nothing to protect wildlife from cats after a PhD study they funded found habitat destruction had more impact than moggies on native mammals.
A thesis by Murdoch University researcher Maggie Lilith will be tabled at Monday night’s council meeting to support a do nothing approach.
Dr Lilith’s 2007 thesis was completed with the help of a grant from the council.
It notes that cat ownership in Australia is declining compared to increasing cat ownership in the United Kingdom, United States and Europe. Dr Lilith believes the decline in Australia may be linked to perceptions of cat predation.
She investigated the abundance and diversity of small mammals in four areas of remnant bushland around Armadale in eastern Perth.
Two areas were beside subdivisions where cat ownership was unrestricted, one next to a housing estate where cat ownership was banned and one beside a subdivision where a compulsory night curfew and bells on pet cats were enforced.
Dr Lilith found no evidence that pet cats had slashed the population of small mammals. Species diversity and abundance was virtually identical from subdivision to subdivision.
She found that the structure and species composition of vegetation differed between most sites. It was this factor, not cats, that appeared to be the main determinant of the richness, diversity and number of small native mammals.
In Armadale, development covenants controlling cats are in place at Waterwheel Estate and Churchmans Brook Estate.
Based on Dr Lilith’s findings, city staff have recommended that nothing more be done until a state-wide cat Bill being drafted by Liberal MP Joe Francis enters Parliament.

1 comment:

Travis Longcore said...

I was interested in this so I read the dissertation. It doesn't exactly say what the article says or what your headline claims. A few things to note.

1. I think there was only 1 cat confirmed in the "free roaming cat" areas that Lilith studied, so it would not surprising not much impact was recorded. This one cat was a stray.

2. The vegetation differed substantially between the treatments, which would mask the impact of any differences in cat abundance. Different vegetation communities would support different small mammal communities. The effects of cat predation, if there are indeed any cats present, would be difficult to detect if comparing areas with different vegetation.

3. The study only included small mammals, not any other wildlife.

4. Lilith recommends the following actions for local governments:
a. A 360 m cat exclusion buffer around natural areas.
b. Registration or identification for all pet cats.
c. Sterilization of all cats not owned by breeders.
d. A limit on the number of cats per household.
e. Moderate confinement of cats such as a dusk to dawn curfew.

Lilith's work, applied to Los Angeles, would lead to cat licensing, cats indoors at night, no cats allowed in natural areas, mandatory spay/neuter, opposition to raising the per house cat limit, and very little tolerance for feral cats (as is generally the case in Australia).

I wouldn't take this study as exonerating feral or even pet cats from harming wildlife by any means. Or as Lilith writes in her dissertation, "establishing the importance of vegetation characteristics is not the same as exonerating cats, as shown by the established cases of cat predation leading to fauna decline in reserves or remnant vegetation (Larkin 1989 and Dufty 1994)."