Technology helping feral cat removal on Aotea, Great Barrier Island

Tū Mai Taonga is undertaking one of the largest feral cat removal operations on an inhabited island, in the world. Cage trapping is the first line of attack. But to try and outsmart the more cunning feral cats - the team is using cutting-edge technology.

Tū Mai Taonga’s ambitious goal is to remove all feral cats from Aotea Great Barrier Island. Once successful, it will be the world’s largest eradication of feral cats on an inhabited island.

Feral cats are the apex predators on Aotea. With no stoats or possums on the island, they are the biggest threat to native birds, reptiles and insects.

“A feral cat’s appetite can be insatiable,” says the Operations Manager in charge of the feral cat eradication, Chris Giblin. “Left uncontrolled, they have decimated the bird population on Aotea, and destroyed reptiles and amphibian populations too, like lizards and frogs. Their hunting capability is enormous.”

The Tū Mai Taonga team has been working on the first of a five-stage, feral cat removal

programme. Zone one is in the northern part of the island, a 4560 hectare block, Te Paparahi, which is largely uninhabited.

The team has cut tracks in dense bush, developed a grid in this area, and deployed remotely monitored traps. From his office in Akapoua, Chris can monitor the traps in real time. The team also has a large trail camera network to monitor progress throughout the project.

“This technology saves us a lot of manpower, but we still manually service the traps twice a week to refresh the lure and respond to any triggers daily. Legally, triggered traps must be checked within 12 hours of sunrise.”

During 2024 most of the feral cats have been removed in zone one, with a small number still to be mopped up. The team is using the camera data to estimate the amount remaining and honing their skills in leg trapping techniques.

“In our first knock down stage we were largely cage trapping,” says Chris. “Now we are in the mopping up phase we are targeting the harder to catch feral cats — the cunning ones. We are trying to outsmart them by identifying their locations and movements through our trail cameras, and then burying leg traps in those areas lightly under some growth. We are experiencing some success with this, which is encouraging.”

Feral cats, the team has discovered, are human-like in their traversing of the environment — they like to walk along ridgelines, fence lines, and tracks and tend to stay on the easiest dry part of the track. That has helped dictate where the traps are positioned. Chris’s team has also learned that feral cats’ favourite bait is rabbit, chicken and fish but are starting trials on alternate long life lures.

The team will take its learnings southward into tackling zone two in 2025.

This is the challenging part of the plan, as it is populated with more humans, and with them, their domestic cats.

Prior to the feral cat removal programme in Te Paparahi, the area was known for its silence, Chris says, because most of the birdlife had been eaten by the feral cats and rodents.

“Anecdotally, we are hearing the birdsong gradually come back,” says Chris. “We are seeing very few feral cats on our monitoring cameras and we are hearing more kakariki and bellbirds,” he says. “The bird calls are what success sounds like to us — and

we are looking forward to moving to a new phase, and the birdsong in Te Paparahi growing louder in the future.”