Wild deer - like possums on stilts

Kerry Hogan’s not sure what he’s done to deserve having most of the feral deer in the North Island on his patch, but it is a problem that is increasingly worrying him.

Deer-ravaged forest. Photo: John Marks

Deer-ravaged forest. Photo: John Marks

Hogan’s beat as Technical Support Manager for the Department of Conservation’s (DOC) East Coast-Hawkes Bay Conservancy covers nearly 600,000-hectares (ha) of conservation land, including Te Urewera National Park and Raukumara, Kaweka and Ruahine Conservation Parks. And deer are a growing problem in much of the huge, rugged expanse of forest here. As with most other parts of the country where there are feral deer, their numbers in East Coast-Hawkes Bay have increased since the collapse of the commercial helicopter deer-hunting industry early this decade.

During a recent visit Hogan shows Forest & Bird Lower North Island Field Office James Griffiths and I an area of the Raukumara Forest Park where deer numbers are low and the forest floor is thick with leaf litter, ferns and other low-growing plants, and a variety of seedlings grow up among the trunks of the mature trees.

In contrast, the forest he shows us at Wahaatua in the Urutawa Forest, north-west of Gisborne, where deer numbers are high, has virtually no seedlings and the understorey is totally absent - all you can see are bare trunks and dirt below the canopy. DOC’s exclosure plots - which fence off areas of forest to monitor the difference between browsed and unbrowsed forest - show a stark contrast: inside the fence is a lush profusion of greenery; outside the ground is bare. Hogan says the deer strip the forest of the palatable species they prefer, such as pate, broadleaf, mahoe, hen and chicken fern and lancewood, reducing the forest to just a few non-palatable species.

The entire understorey of leafy shrubs vanishes, along with the tree seedlings that would have eventually replaced the mature canopy trees. Ground-covering plants and leaf litter are also gone, leaving the forest floor exposed to the impact of rainstorms and erosion. The food sources of fruit, seeds, insects and leaves that would feed native birds disappear; so does habitat for the birds and the myriad invertebrate species of the forest floor.

The forest he shows us at Otamatuna Mainland Island in Te Urewera National Park, where intensive control of deer and other pests is conducted over 2500-ha, is in good health. Palatable species such as native fuchsia, which wouldn’t stand a chance against high deer numbers, are thriving.

Monitoring of faecal pellet indexes show that if deer control is effective enough to produce less than three per cent incidence of deer droppings along the monitoring lines, that is enough to allow recovery of the shrub tier here.

Hogan and the East Coast-Hawkes Bay region are not alone in facing an increasing deer problem. Senior Technical Support Officer at DOC, Keith Briden, says the last estimate of New Zealand’s feral deer population was made in about 2000, and put numbers then at 250,000 nationally.

There have been wild deer in New Zealand since they were liberated here in the 1850s. From the 1950s-1970s, the Government paid deer cullers to shoot deer from the ground, till the commercial deer-hunting industry shooting deer from helicopters effectively took over. Commercial deer-hunters were killing 18,000-20,000 deer a year, but since international venison markets slumped, the industry has been taking just 1000-3000 deer a year. Last year the take was up slightly to 5483, but the industry is virtually at a standstill. DOC doesn’t have figures on how many deer recreational hunters take: New Zealand Deerstalkers Association spokesman Hugh Barr says a study in the late 1980s put the figure at 50,000 a year.

Briden is reluctant to hazard a guess at how much the deer population has increased since commercial deer hunting ceased, but he says deer population increases are a concern, particularly in Fiordland, South Westland and the Urewera Ranges. Of particular concern is the reappearance of deer on the high tops, where they were greatly reduced by helicopter hunting and where vegetation had been recovering well.

Former Director-General of Conservation, Hugh Logan, warned on his departure from the job a year ago of the threat of rising feral deer numbers - he believed wild deer populations in Fiordland and the northern East Coast could be doubling every two years. However, the extent of deer control being carried out is negligible: publicly funded deer control is carried out on just 1.3% of the area where feral deer are found. DOC’s map showing deer control operations shows them as pitifully small spots of red in an expanse of feral deer range.

Briden explains that DOC priorities mean that pest control resources go first to target predators, particularly where they threaten to push endangered species to extinction. Deer - further down the ladder of priorities - miss out. Paying hunters to kill feral deer would only result in deer being removed from the most accessible country, leaving deer in the more inaccessible back country.

He agrees tenders could be sought for hunters to shoot deer in specific areas, but policy dictates that “market forces” hold sway, and paying people to kill deer is seen as “subsidies” and therefore a no-go. Briden is hoping for the recovery of venison markets, and says DOC is “holding off” for another year or so for that much-hoped-for revival, though he admits that pinning the fortunes of deer control to a boom-and-bust industry is not the most reliable long-term solution. Hogan is wary of “wait and see”. “It’s not panic stations yet, but we need to start making decisions about what we are going to do. The problem isn’t going away.” He suggests “incentives” for the deer industry could support a solution that produces gains for both conservation and the industry. The current price of venison at $2.50 a kilogram (down from a peak of more than $8) means commercial hunting simply isn’t financially viable - but if the price reached around the $5 mark, the helicopters could be whirring back into action.

He suggests that top-up payments for each deer killed by commercial hunters could fund effective deer control at a fraction of the estimated cost to DOC of $150 per deer if it undertook deer control on its own. To avoid deer hunters taking only the easy meat, payments could be conditional on hunters taking out a guaranteed number of deer from an area.

Hogan is optimistic about the chances of recovery of forests if deer are reduced. “In just about every [deer] exclosure plot I have ever seen, there is a huge variety of species that come back - I am amazed by the resilience of the seed sources. But the longer you wait, the more you put that at risk. And any improvement is better than nothing, even if you don’t get back exactly what was there in eighteen hundred and whatever.”

DOC remains unconvinced that recreational hunters can play a major role in controlling deer, particularly on the rugged back country. Hogan - a former deer culler himself - says he had a quota of 20 deer a month, while commercial hunters with helicopters would take 10 times that many. A study by Landcare Research for DOC undertaken from 1997-2006 in Kaweka Forest compared the survival rate of mountain beech seedlings in areas fenced off from deer, areas where deer were aerially hunted and areas where they were recreationally hunted. The study found seedling survival and forest recovery was highest in fenced areas, moderate in areas where aerially hunting took place, and lowest in recreational hunting areas.

However, the Deerstalkers Association believes recreational hunters can play a valuable complementary role in controlling deer, particularly in more accessible hunting spots. Barr says claims that deer numbers are dramatically increasing and causing serious damage are “significantly overblown”. His own experience tramping since the 1950s is that deer numbers and damage are much lower now than they were at their peak in the middle of last century.

Barr is a member of a ministerial panel reviewing management of deer, chamois, tahr and pigs in the wild (Forest & Bird’s Sue Maturin is also a member). The Deerstalkers Association will seek to have the panel acknowledge deer as a valued recreational species, rather than a pest. But Barr says deerhunters don’t want high deer numbers - deer are in poor condition when populations are high and make poor eating - and so they want to see a management regime introduced as much as conservationists do.

Forest & Bird Advocacy Manager Kevin Hackwell is increasingly worried by the fact that there has not been any effective control of deer for several decades. He says even commercial hunting had a limited effect because, while it was relatively easy to take deer from the tops and more open country, deer populations remained virtually untouched in more dense forest where the helicopters couldn’t reach them. “We know the damage is serious and is getting worse. Walking into many of our forests is like entering an empty cathedral - while there may be a fine canopy overhead, below there is just empty space.” In some forest areas we are already starting to see total forest collapse caused by deer, Hackwell says. “If we don’t move on deer control, the longer we wait the harder it is going to be to achieve recovery of the forests.” Damage to the canopy and understorey also increases vulnerability to floods and erosion, he says. Heavily browsed forest offers little protection from heavy rain reaching ground level, or from run-off, so catchments suffer much worse effects.

Hackwell says increasing financial pressure on New Zealand to meet its international obligations to reduce greenhouse gas emissions may be the catalyst that sees deer control become not only affordable but a financial necessity. Reducing the amount of forest destroyed by deer (and other introduced browsers) would greatly increase the amount of carbon stored in our forests. Greater deer control would also reduce the amount of the greenhouse gas methane that is produced by deer. Cutting wild deer numbers could significantly reduce New Zealand’s greenhouse gas liabilities, potentially saving the country hundreds of millions of dollars. That would pay for the cost of deer control many times over.

Recreational and commercial deer-hunters may not provide the entire solution to the deer problem, but they can certainly be part of it, Hackwell says. However, he says the bid by the Deerstalkers Association to have deer granted valued status is not helpful. “Sadly, some hunters want to go from being an important part of the solution to being part of the problem. They want the Government, farmers, foresters and other landowners to have to manage these pests for the hunters’ benefit, rather than for the protection of the environment.” The fact that deer-hunters find value in the recreation they get from hunting deer does not remove the fact that deer are introduced pests that are causing serious damage to the environment, Hackwell says. “The options come down to choosing between an introduced pest and our native forests and unique endemic species such as kiwi. I know which option I - and most New Zealanders - would choose.”

(Forest & Bird magazine article by Helen Bain, November 2007)