The Department of Conservation plans to increase predator control in South Island beech forests as forecast mass seeding this summer puts vulnerable native wildlife at high risk from introduced predators.

The predicted beech mast will drop trillions of seeds, fuelling a surge in rodents then stoats – with potentially devastating impacts on native birds, bats, snails and other species.

DOC National Predator Control Programme Manager Peter Morton said it is expected to be the biggest beech mast in seven years with seeding most likely in western areas from Kahurangi at the top of the South Island to Fiordland.

“We are planning a bigger predator control programme than usual over the next two years to protect our most vulnerable native species like mohua, rock wren and pekapeka from beech-seed fuelled plagues of rats and stoats,” Morton said.

“Operations will be focused on the best surviving populations of endangered wildlife in Kahurangi, Mt Aspiring, Arthur’s Pass and Fiordland national parks,” he said.

“We know if we do nothing, native species will be decimated. Some of our last surviving mohua populations are hanging on by a thread and there’s a risk with a surge in predators we could lose them,” Morton said.

A rat plague during a beech mast in 1999 wiped out the last population of yellowhead in the northern South Island at Mt Stokes, as the birds are helpless when rats invade the tree holes where they nest and roost.

“Our monitoring shows that carefully timed aerial 1080 operations prevent large spikes in predator numbers, enabling birds and bats to survive and breed successfully. Controlling predators is one of the most important actions we can take to protect nature,” he said.

Planning is underway for 15 predator control operations over 650,000ha at priority South Island sites from spring to early summer. This is in addition to DOC’s regular programme over another 150,000ha.