New Zealand will need to make major advances in large-scale predator management to stop and reverse forest bird
New research from Manaaki Whenua – Landcare Research has found that native forest birds which are vulnerable to
predators are becoming more confined to higher, colder parts of remaining forests.
The main reason for what scientists are dubbing a ‘thermal squeeze’ is likely to be more relentless pressure from
greater numbers of predators in lower, warmer forests.
The situation is likely to worsen with climate change, which will reduce the extent of cooler refuges where predator
numbers are lower most of the time.
Manaaki Whenua – Landcare Research wildlife ecologist John Innes says the study powerfully extracts new insights from
past New Zealand Ornithological Society Atlas surveys undertaken by volunteer birdwatchers across the country.
“They would be pleased to know that their many weeks of noting birds is now helping to conserve them,“ he says. “This
study adds a sharp new conservation twist to the threats from global warming. Predators like ship rats and stoats are
already a problem, but these results suggest that impacts may be greater in the future.”
The forest bird species most imminently endangered by thermal squeeze in New Zealand are larger-bodied and include some
of the rarest forest birds remaining on the mainland such as kiwi, whio, weka, and kōkako. Birds that nest in holes and
are therefore vulnerable to being attacked and eaten on the nest, are the next most vulnerable. This includes rifleman,
mohua, kākā, kea, and kākāriki.