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.