Wild deer numbers have climbed back to the levels New Zealand last saw in the 1950s and 1960s, and three of the country’s senior forest ecologists say the result is a native forest that looks healthy from the outside while being quietly emptied from the inside.
Their warning appears in a paper published on Monday in the New Zealand Journal of Ecology, written by University of Canterbury emeritus professor David Norton with Peter Bellingham and Sarah Richardson of Manaaki Whenua–Landcare Research. The authors argue the country is, in their words, “sleepwalking our way to a native forest catastrophe”, and they call for a national deer management strategy that puts native biodiversity and climate resilience ahead of every other consideration.
Norton told RNZ the damage is easy to miss because the biggest trees are the last to go. “Our mature canopy trees, whether they’re podocarps or beech trees, they live for many decades and they’re not going to necessarily disappear because of deer today,” he said. “But it’s the regeneration that’s coming away underneath that is a real concern.”
In the worst affected places, he said, that middle layer has already gone. “There’s a layer of moss on the forest floor; there’s a canopy of silver beech trees 20, 30 metres up – nothing in between.” He named South Westland and western Otago as areas where the forest floor has been stripped of the seedlings, saplings and shrubs that should be filling the gap between ground and canopy.
The mechanism is not dramatic and it is not fast. Deer are fussy eaters. The Department of Conservation notes that they work through their preferred species first, plants such as schefflera and broadleaf, and then move on to less palatable ones, which changes the mix of plants that survive and can hinder or stop forest regeneration altogether. The plants that vanish are also the ones that feed and shelter native birds, insects and lizards, so the loss runs well beyond the trees themselves.
Seven deer species are now established here, red deer being the most widespread, descended from releases that began in 1851. DOC says harvesting has not kept pace with breeding for the past couple of decades. Its own monitoring backs that up. Across the sites it tracks, the number of deer and other wild animal droppings counted almost doubled between 2013 and 2022, which is the department’s standard proxy for how many animals are out there.
What worries Norton most is what happens when browsing pressure meets a run of bad weather. “We’re getting more intense storm events. We’re getting drier summers. Our forests have tolerated disturbances and extreme events in the past,” he told RNZ. “But when we add deer into it, I think there’s a real concern there that the two things together may lead to a much more pronounced forest collapse, and that will then have downstream effects.” A hillside that slips and then regrows is a hillside that holds together next time. A hillside that slips and is grazed bare as it tries to regrow is not.
Explore the data. See how much native forest each region has lost since people arrived, and how much is left today, in our interactive native forest tool.
The paper lands in something of a policy vacuum. In March, the West Coast Conservation Board heard from farmers and board members that deer pressure in South Westland was, as they put it, the worst it had ever been. Asked at that meeting whether a control plan existed, DOC wild animals manager Mike Perry told the board, “No, is the short answer.” Board member Rob Wilson said the public wanted a say. “There is a huge public interest in controlling deer numbers. The deer numbers are going up and everybody’s complaining about it, but I think there is an obligation to involve the public,” he said.
Norton and his co-authors are not calling for deer to be wiped out everywhere. Their proposal is a national strategy that would push numbers close to zero in the places where forests are most vulnerable, while allowing managed herds to remain elsewhere, with conservation groups, iwi, hunters and farmers all at the table. Norton was blunt about the order of priorities. “But I do believe as an ecologist, the first priority has to be biodiversity conservation and landscape resilience,” he told RNZ. “Hunting opportunities, recreational opportunities have to come in underneath that.”
That ordering is where the argument will happen. Hunting is a large part of how deer are kept in check now, and hunters have long argued they are the practical answer rather than the problem. ACT on Saturday proposed shifting responsibility for game animals on conservation land from DOC to the Game Animal Council, with the party’s conservation spokesperson Cameron Luxton saying it was about recognising hunters as the “conservationists they are”. There are working examples of the two sides pulling together. In April the Canterbury charity Hunters4Hope began culling deer in DOC reserves on Banks Peninsula and passing the venison on to families who needed it, which took animals out of the bush and put food on tables at the same time.
What the ecologists are asking for is a plan that says which forests matter most and how many deer each one can carry, rather than the current patchwork of local operations and goodwill. Forests take a very long time to grow back. The seedlings that should be replacing today’s rimu and silver beech are the ones being eaten now, and the bill for that arrives decades after the animals have moved on.
Have you noticed the bush changing where you tramp or hunt? Tell us what you are seeing in the comments below.
This article was written by AI, briefed to report the facts, hopefully without some of the bias people bring to the job 🙂
Leave a Reply