No mice detected in Rakiura survey

Environment Southland has completed its hunt for mice on Stewart Island Rakiura – with great results: no evidence of the small rodents detected!

The council’s biosecurity and biodiversity operations manager Ali Meade said 26 rats were trapped during the project, which began earlier this month.

In 2023, a camera survey undertaken by Predator Free Rakiura showed images of small rodents which could have been mice on the island.

As a result, Environment Southland launched a survey project in the same areas to see if they could determine whether there was an established population of mice present on Stewart Island Rakiura.

Contractors set up bait stations, traps, and cameras at eight sites, which were monitored for two weeks before being removed.

“Most of the rats captured were kiore (Pacific rat). Some of them are very small, and one was caught in a mouse trap. The images captured by Predator Free Rakiura in 2023 are likely to have been of a small kiore, not of a mouse,” Ali Meade said.

While Environment Southland’s survey results do not prove that mice aren’t present on Stewart Island Rakiura, the results are very encouraging.

“It’s great that we don’t have evidence of an established population of mice, but we still need everyone to do their part in making sure they don’t accidentally take mice to Stewart Island Rakiura, as this could have terrible consequences for conservation efforts and most importantly, our taonga (treasured) species,” she said.

Rodents, including mice, can have devastating impacts on New Zealand’s ecosystem and taonga species. Mice can form huge populations quickly, and have been known to eat bird chicks, especially those in ground nests. They compete with native birds by eating many of the same foods like seeds and invertebrates. When mice eat seeds they destroy them, whereas when birds eat fruits and seeds, the seeds usually survive through the digestive tract and are dispersed as a natural way for native trees to colonise new areas.

It’s vital that everyone travelling to Stewart Island Rakiura and its surrounding islands remains vigilant by thoroughly checking their gear for any unwanted stowaways.