Scientist backs Gareth Morgan’s cat claims

Scientist backs Gareth Morgan's cat claims (Source: ONE News)

A scientist is backing Gareth Morgan’s campaign to control cats, but says more needs to be done to curb other species.

Economist Gareth Morgan launched the Cats to Go website yesterday, which claims New Zealand’s native birdlife is being decimated by domesticated cats.

The campaign encourages cat owners not to replace their cats when they die in order to protect native bird species.

Today, University of Otago senior lecturer in Zoology, Dr Yolanda van Heezik, said that she supports most of Morgan’s claims.

“I support Gareth Morgan in his campaign to raise awareness about the impacts that pet, stray, and feral cats have on our native wildlife,” she said.

“The recommendations given by Gareth Morgan are reasonable. Consider using a collar with a bell: our research has shown they reduced catch by 50%.”

Van Heezik said she suspects that most people have never given the issue much thought, or they think that the one or two birds caught by their own cat makes no difference.

“Other countries such as Australia have regulations in place around cat ownership and cat movements, and we need to start thinking along the same lines,” she said.

People need to consider that cats exist across cities at a density of about 225 per square kilometres, and that even though individual cats may catch few birds, cumulatively the total of birds killed is large.

‘Pet cats catch birds’

Van Heezik referred to three studies quantifying the prey caught by domestic cats in New Zealand (in Auckland, Christchurch and in Dunedin) which all agree that pet cats catch birds, including native species.

Cats appear to catch species in proportion to their abundance in the environment, so in Dunedin, the two most abundant bird species (silvereyes and house sparrows) were the two most common bird species caught by cats.

The study identified that about one third of cats did not bring any prey home, about a half brought back prey infrequently, but that about 20% were frequent hunters.

“The average number of prey brought back per year was 13, but that included rats, mice, lizards and invertebrates,” she said.

“Consider keeping your cat inside at all times. This ruling is in effect already in some parts of Australia. And consider not replacing your cat when it eventually dies.”

Impact of cats is ‘controversial’

Landcare Research scientist John Innes said it seems Morgan is aware that there are other predator species to consider besides cats.

“The impact of cats  – whether feral or pet – on valued wildlife remains controversial because it is site-dependent and ecologically complex, and because key impact questions are frequently unresearched.

“In New Zealand native forests, ship rats are the major prey, and this little-seen predator eats many more birds than cats do,” said Innes.

“The Gareth Morgan website refers to kaka, kokako, weka, mohua, t?eke and robins as endangered, perhaps implying that cat control might help them, but cats are not significant predators of any of these species, except possibly weka.”

Innes said he agreed with Cats to Go website’s claim that cats and rats need to be controlled together.

“In fact recent thinking around a Predator Free New Zealand has always focused on several species, usually stoats, ship rats and possums.  Whether mice, hedgehogs, Norway rats, ferrets, weasels and cats may yet be included is still unfolding.

“In the meantime, pet cat owners should educate themselves about the possible threats of their cats to local wildlife,” he said.

Read more: