Source: Department of Conservation
Date: 23 January 2025
Ulva Island is a nature sanctuary in Paterson Inlet, 780 metres from Stewart Island/Rakiura. It is popular with visitors who come to experience the thriving wildlife.
It first achieved predator-free status in 1997 and has become a sanctuary for many native species, including Stewart Island brown kiwi/tokoeka, kākā, kākāriki, yellowhead/mohua, and South Island saddleback/tīeke.
DOC Acting Operations Manager for Rakiura, Bridget Carter, says intensive monitoring for rats is underway on Ulva Island.
“Our incursion response kicked into immediate action last week and the team has 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 sign and catch any remaining rats. Toxin may be used sparingly where rats are known to be present but avoid traps.
“Although detecting rats on the island is disappointing, it does show the biosecurity monitoring system is working as it should,” says Bridget.
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. This risk increases when rat numbers are high on the mainland due to warm weather and food availability.
Visitors are being asked to keep an eye out for any signs of rat presence on Ulva Island – please take photos, record the location and report it to the DOC Rakiura Office.
DOC carried out a successful eradication operation on Ulva Island in the winter of 2023 after a breeding population of rats established on the island. The island was declared rat-free again in early 2024.
A single rat was caught in February 2024, with genetic analysis indicating this individual was not a survivor from the 2023 eradication. Intensive monitoring using a variety of methods following this incursion event showed the island was again free of rodents.
The risk of ongoing rat incursions on Ulva Island remains high while rats are present on Rakiura, and intensive biosecurity monitoring systems are needed to enable an effective response to protect Ulva Island’s predator-free status.
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