Tuesday, May 29, 2018

New Zealand's Feral Spree Killers

New Zealand is trying to protect
its wild places and wildlife, but to do that they need to kill off non-native stoats and feral cats as well as rats, possums, and ferrets.

The New Zealand Department of Conservation did a recent survey of the resident bat population on southern Mount Ruapehu.

They net the bats, put a transmitter on them, and then track them back to their colony trees. Bats are the only native mammal in New Zealand.

One massive beech tree on the southern slope of Mt Ruapehu is called "The Mothership" and it can house more than 1000 short-tailed bats. A hop and a skip away is another massive tree dubbed "Notre Damme," which can house another 2000 bats.

But it only takes one feral cat to wipe out all the bats in a colony, as the cats are not even eating for food. This is "spree killing" of the kind practiced by cat and fox inside a chicken coop.

Twenty-four hours after setting out a cat trap at the base of The Mothership, Malcolm Swanney - a local DOC ranger - returns to the office with his prize and a big grin. A male tabby cat, surprisingly heavy for its small size, and although its stomach reveals no evidence of bat remains, the bite size matches exactly those found on the dead bats. The roosts continue to be watched, and as the days go by with no more wings or bodies found, and no more cats caught, the rangers finally begin to relax.

In the space of 7 days, one cat killed a total of 102 bats, and these only the ones that were found. "This really highlights the impact that cats can have on native wildlife, and I don’t think a lot of people realise what skilled predators cats really are. It’s one thing to suspect predation occurs, another thing entirely to actually witness the damage one cat can do." - Jess Scrimgeour, DOC scientist.

Bottom line: The best feral cat is a dead feral cat. We need to adopt a zero tolerance policy on islands and near bird colonies, and impose Trap, Kill and Bury regimes at these locations.


Jennifer said...

Unfortunately, Predator Free New Zealand is too timid to put cats on its kill list. I don't really blame them, though exclusion of cats defeats the purpose of Predator Free. Cat lovers are many and they go bonkers when you suggest anything that has a hope of eliminating farel cats. I've gotten nasty comments on FB for voicing the opinion that people should keep their cats indoors.

Garnet said...

I agree - not putting cats on there does defeat the purpose of the whole thing as cats can be very effective predators. I have visited New Zealand (including offshore island bird sanctuaries) and some of the birds there are simply not afraid of mammals. I had a few Weka and a small robin walk right on my feet. Cats can easily decimate bird populations, especially when said birds are not adapted to the presence of cats.

I like cats and have two but keep them inside. One is actually a friendly stray I kept upon failing to find an owner. I had her spayed and vetted. However, when it comes down to cats vs endangered birds, well...the birds have to come first, as there's certainly no cat shortage going on but a lot of New Zealand bird species are vulnerable or endangered. Feral cats aren't pets and should be treated as feral wild animals. That can mean having to control their numbers in some instances. Feral cat lovers can round them up and keep them in enclosed colonies if they want to save them that badly.

Garnet said...

Oh yes, New Zealand bats will forage on the forest floor, making them quite vulnerable to cat predation. Trap/neuter/release isn't helpful with protecting bats from cats, as a neutered cat may still kill a lot of bats in its lifetime. Eliminating cats, as distasteful as it is, is the best way to protect these bats.

LRM said...

God, this is depressing. I’ve had the same arguments, locally and online, with cat owners who are defiantly ignorant about the damage their outdoor felines do. Even when confronted with substantial data (indeed, in spite of it), the bias persists.