Oh deer: The threat munching its way through NZ's native forests
The need for a national deer management strategy to manage the decline of native forests is highlighted in a new research paper published today in the New Zealand Journal of Ecology. Led by Te Whare Wānanga o Waitaha | University of Canterbury (UC) Emeritus Professor David Norton, the paper, "Deer in the headlights: sleepwalking our way to a native forest catastrophe," warns of a slowly developing crisis that is often hard to see.
"Our mature trees can live for three, four or five hundred years, so we're looking at centuries-long replacement cycles and aren't seeing changes happening overnight," Norton says.
"You can walk into a forest and see a beautiful canopy, but there may be nothing underneath it except moss because deer have taken out the intermediate layer. The forest is still there and looks beautiful, but when it goes through its replacement cycle, a lot of those elements like seedlings and shrubs aren't there anymore."
The damage caused by deer goes beyond just eating plants, Norton says.
"Deer also damage forests by trampling the forest floor. Unlike moa, the large native birds that once moved through New Zealand forests on broad, avian feet, deer have narrow, cloven hooves that exert much greater pressure on the ground. This removes leaf litter, compacts the soil and can affect water infiltration and overall soil health.
"While as an ecologist I would like to see no deer in New Zealand, this is not going to happen because they've also got social value, so I think we need to look at New Zealand native forests and ask which areas are high priorities for biodiversity conservation and climate change resilience, where we should be trying to get rid of all deer, and where we can accept the presence of a well-managed deer herd for recreational hunting.
"We need to work in partnership—hunters and conservationists, farmers and plantation foresters, government and iwi—because we all want to have a livable country and we want this environment to be here in the future."
Before people arrived, around 75% to 80% of Aotearoa New Zealand was covered in native forest. Today, that figure is about 25% to 30%, Norton says.
He says native forests provide more than recreational value for New Zealanders.
"Our forests provide us with a massive amount of resilience. They're a huge store of carbon, they provide habitat for so much of our flora and fauna, and they protect our watersheds and look after our downstream human communities.
"If forests start collapsing or changing and we have intense rainfall events, which are increasing due to climate change, less water and sediment will be held back in the system, and we will see more damage downstream.
"Broadleaf is a really good example of deer impacts. You can see the foliage starts at the height to which a deer browses, and there's nothing below that. At some point, when those trees die, there are no more seedlings coming in and it will disappear."
More information
David Norton et al, Deer in the headlights: sleepwalking our way to a native forest catastrophe, New Zealand Journal of Ecology (2026). DOI: 10.20417/nzjecol.50.3639
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Citation: Oh deer: The threat munching its way through NZ's native forests (2026, July 27) retrieved 27 July 2026 from https://phys.org/news/2026-07-deer-threat-munching-nz-native.html
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