Science Express: The Ecological View of Cats
Thursday 4 April 2013,
Level 4 Espresso
Join former DSIR (Department of Scientific and Industrial Research) scientist John Flux to learn where domestic cats fit in the complex hierarchy of good and bad predators.
The domestic cat is New Zealand's top carnivore. In the light of recent publicity and ill-informed debate, John will address two critical points: what are the effects of cats on wildlife, and what would happen if cats were removed?
John studied the effect of his suburban cat for 17 years and compared the results with a 15-year period without a cat. He discovered his cat clearly had a beneficial effect on native wildlife, but does this hold for other cats in other areas? Most studies support his conclusion, apart from those involving cats on small islands and in Dunedin.
The second point is more complicated. Cats kill stoats, weasels, rats, mice, lizards, and insects. Killing stoats is good, because they generally eat more birds than rats. Killing weasels is bad because they eat more rats and mice than birds. Killing rats is mainly good, but rats keep down mice very efficiently, and mice are probably the worst predator of lizards and insects. Removing one type of predator results in unpredictable changes in the numbers of all the others. The only safe way is to start with the mice, and work up the chain.
John Flux was a scientist in Ecology Division, DSIR, for 35 years, studying the behaviour and population dynamics of hares, rabbits, and starlings.