An explosion in rat numbers in the South Island this summer could put rodent-free conservation land at risk, the Department of Conservation says.
DOC said yesterday many areas in the South Island would experience high numbers of rats and mice due to a high seed fall last autumn,
providing more food for the rodents.
DOC Fiordland project manager for islands Kerri-Anne Edge said an increase in the number of rodents occurred every three to five years but this year the "numbers have exploded".
While an exact number could not be known, monitoring stations in parts of Fiordland had reported a 90 per cent increase in rodent activity.
Numbers were being managed in rodent control areas.
A programme - Ark - was established three years ago when the need for a management programme was identified.
Dr Edge said Ark was aimed at ongoing rodent and stoat control - not just in plague years.
"The main thing for holidaymakers in the South Island to be aware of is not to be surprised if you're going camping and you see rats," she said.
"It's critical if going boating to any of the islands anywhere in the South Island to check camping equipment and boats for rodents."
Dr Edge said some South Island islands were rodent-free and it was essential people did not inadvertently introduce them.
"Secretary Island in Doubtful Sound is a good example of that," she said.
"It's 8000ha which has never had rats or mice and boaties going there could easily transport rodents from the mainland."
Te Anau Mitre 10 manager Neil Hodges said there had been an increase in sales of rat traps in the town.
"We've seen a few around town, but they're mainly in the country where there's more food," he said.
- NZPA
