The Department of Conservation (DOC) said an incursion response started on Ulva Island after a rat was found dead in a trap last week during routine surveillance.
DOC Acting Operations Manager for Rakiura Bridget Carter, said the incursion response kicked into immediate action and the team had been checking traps and using lured cameras and rodent detection dogs to determine the extent of rat presence.
“Since the dead rat was found on 13 January, rat activity has also been captured on trail cameras. Further monitoring will tell us if this is a single rat or more.
“Our plan from here is to continue with increased surveillance and ongoing trapping efforts to monitor for further signs and catch any remaining rats. Toxin may be used sparingly where rats are known to be present but avoid traps.’’
She said although detecting rats on the island was disappointing, it did show the biosecurity monitoring system was working as it should.
On average one or two rats manage to find their way to Ulva Island each year due to its proximity to Rakiura where rats are present.
The risk increased when rat numbers were high on the mainland due to warm weather and food availability, she said.
Ulva Island was declared rat-free again in early 2024 after a breeding population of rats established on the island in 2023.
