Image of the August 2022 Wilderness Magazine Cover Read more from the
August 2022 Issue
Home / Articles / Walkshorts

Rats outwit eradication efforts on Ulva Island

Ulva Island is 800m off Rakiura/Stewart Island, a swimmable distance for rats. Photo: G Lind/DOC

Rats rule Ulva Island, and DOC says efforts to stamp out the pest since February have failed.

The island is a sanctuary for native birds and achieved predator-free status in 1997.

Located just 800m off Rakiura/Stewart Island, Ulva is within swimming distance for rats – and until now, incursions of the pest have been successfully thwarted.

In February, though, a dead Norway rat was found in a trap on Ulva, and in June a spokesperson for DOC said the department would consult with the Rakiura community over plans to handle this situation.

By early July, the consultation process was yet to begin.

Ulva Goodwillie, who operates walking tours on the island, believes the rats should never have been allowed to get out of control.

“The last big incursion was in 2010, so DOC has a full rundown of the processes that should have been followed,” Goodwillie said.

DOC Rakiura operations manager Ren Leppens said Brodifacoum pellets were used in late April and early May after traps failed to catch a ‘device shy’ breeding pair. The pellets were also unsuccessful.

“This was most likely due to the high levels of forest fruit available, providing the naturally cautious Norway rats  with abundant familiar food sources,” Leppens said.

“The issue with ongoing rat invasions on the island highlights the benefits of a predator-free Rakiura, as once rats have been eradicated from the Rakiura mainland, Ulva Island will be significantly more secure as a sanctuary for our treasured biodiversity.”