A pet cat in rural Waikato is responsible for the deaths of six native New Zealand bats threatened with extinction, according to research by the Department of Conservation (DOC).
Along with the deaths, the pet cat had also injured a seventh bat, all in the space of two years.
The researchers also found the remains of at least one bat in a feral cat trapped near a maternity roost tree in a Waikato forest.
They say the cases are just the tip of the iceberg, given cats are known predators of bats.
Their findings have recently been published in the New Zealand Journal of Zoology. They say it confirms what has long been suspected - feral and pet cats are repeatedly hunting and eating the country's bats.
The research detailed how on January 25, 2020, DOC staff were contacted as an injured bat had been found in a house around 20km southwest of Ōtorohanga.
Three dead bats - two in the driveway and one on the doorstep - had been discovered the day before.
The injured bat was identified as a juvenile male long-tailed bat. It mainly had tears in its right wing.
After being taken to the vet for treatment, it was released that night.
However, it was found the next morning on the trunk of a tree with more injuries, including a puncture wound to its shoulder.
One of the authors, Lucy Bridgman, took the bat to the vet again and then cared for it for four days, but it was euthanised due to a lack of improvement and a high likelihood of broken bones.
Its bones were unlikely to repair adequately for a safe release.
All four of the bats were then necropsied, with three of them swabbed for cat DNA.
Three of the bats had multiple puncture wounds to one or both wings and one had a suspected puncture wound to its pectoral muscle.
"The diagnosis was consistent with cat predation," the research noted.
The research also noted DOC was contacted on February 9, 2021, to say two more dead bats and an injured one had been found on the Waikato property.
After receiving vet care, the injured bat was successfully released the following night.
The pet cat's kills and injuries has led author Kerry Borkin to describe it as a "serial pekapeka killer". However, she said DOC are "grateful" the cat's owners reached out.
"We've now got conclusive evidence a pet cat will attack and kill native bats over several years, and that's important to know when protecting New Zealand's only native land mammals," she said.
Given long-tailed bats only weigh as much as a $2 coin, Borkin said it's no surprise cats are coming out on top. She explained pekapeka are attacked when they're in their roosts and flying.
'Horror' as almost entire bat found in feral cat
The research also looked at the stomach contents of a feral cat trapped in the Pureora Forest Park.
Cat scat had been found near a lesser known short-tailed bat maternity roost tree on January 25, 2020. Female bats gather in such trees to raise their young over summer.
Three cat traps were set nearby and two were later trapped - a male on February 18 and a female on February 27.
The scat and gastrointestinal tracts of both cats were examined.
Remains of tree wētā, manuka beetle, rat and huhu were found in the cat scat.
Multiple rats and tree wētā were found in the gastrointestinal tract of the male cat, while rats, wētā and at least one lesser short-tailed bat were found in the female.
"To our horror there was almost an entire bat in there," Borkin told 1News.
An entire head and wing parts, including the wing membrane, wrist, thumb and metacarpals, were found.
Borkin said cat owners can make their pets more conservation-friendly by taking a quiz on DOC's website.
DOC has a legislated mandate to control feral cats on public conservation land. It does so where native species - including pekapeka - are under threat.
"Native bats can be found in towns, cities, farms, and forests - if cats are there too, then bats are at risk of being killed," Borkin said.