The Department of Conservation (DOC) plans to increase predator control in South Island beech forests including Mt Aspiring National Park 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’s expected to be the biggest beech mast in seven years.

“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,” Peter said.

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

Without action, native species in these national parks will be decimated, Peter said.

“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.”

Mohua/yellowhead 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,” Peter said.

A collaborative predator control effort by Southern Lakes Sanctuary, DOC, and Forest and Bird Central Otago curbed the ‘rat plague’ of the 2023/24 summer.

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“Controlling predators is one of the most important actions we can take to protect nature,” Peter said.

Beech mast response operations will be focused in two rounds – later this year before seed falls in autumn and from late 2026, once seed has been eaten or germinated. 

This avoids times when beech seed carpets the forest floor and rodents are less likely to eat toxic bait.

PHOTO: Marty Taylor/NZ Geographic