Droppings from Northland forest used to help eradicate feral deer

Professional hunter Jordan Munn (Upper Hutt) with a sample of deer droppings collected for DNA analysis, while Andre Witehira (Rawhiti) observes.

Droppings from a herd of several dozen deer living in and around the Russell Forest are being collected for DNA analysis as part of a plan to eradicate the animals within the next three years.

Iwi, DoC and the Northland Regional Council share a vision of a deer-free Northland, central to which is eradicating the wild offspring of sika deer (Cervus nippon) that were illegally released into the Russell Forest in the late 1980s, and others thought to have been unlawfully liberated there since.

Despite ongoing, and successful, efforts to reduce their environmental impacts and prevent the deer spreading to other parts of the region, officials have been unable to eradicate them altogether, estimating there are now 50 to 60 animals living in the forest and on surrounding farmland.

Jack Craw, chairman of the regional council's Biosecurity and Biodiversity Working Party, said it was estimated the herd could double in size in the next three years, and that was where DNA testing has an important role to play.

The DNA survey on a large property in the Russell area was the first step towards eradication of the pests.

"It will be a 'proof of concept' to provide costs and effort data that can be modelled for the wider Russell Forest sika eradication," Craw said.

The farm was chosen because it was known to have sika living and potentially breeding there.

The survey involved collecting sika scat/pellets along set transect lines across the roughly 700ha property. Each sample was recorded using GPS and was then sent to a laboratory to be analysed.

"The DNA will be able to tell us the number of individuals, the sex and the home range of each sika on the property," he said.

The methodology for the survey is based on science, expert technical advice and advice from Norm MacDonald, a deer eradication expert from the Department of Conservation who haa international experience in large mammal eradications.

The council said the project also aimed to empower hapū in their kaitiaki role in Russell, and ensure their sustained involvement in keeping pests, particularly wild deer, out of the forest.

NRC biosecurity manager Don McKenzie said there had been no known feral deer in Northland 30 years ago, but they were now thought to be living in the wild in more than half a dozen locations, most the legacy of farm escapes, the balance being illegal liberations sourced from other parts of the country.

Feral deer were officially classed as an "eradication species" in the north, and, while their combined numbers weren't huge, they're were definitely not wanted. It was illegal to release deer, or move wild deer in or around the region.

Community leaders and local hapu had made it clear through correspondence and hui that wild deer were not wanted in Russell, or in Northland.

Letters of support and endorsement for the latest operation had been received from the Northland and Te Hiku Conservation Boards, and DoC's Director-General.

Craw said feral deer were an issue because the animals were selective browsers, targeting particular forest species over others, which could substantially alter a forest's make-up, along with associated negative impacts on the fauna that relied on those plants.

As well as destroying the understorey of native forest by browsing, grazing, bark-stripping and trampling (which could all increase soil erosion), they could also damage crops and exotic forests, and had been implicated in the transmission of bovine tuberculosis, he said.

"Similarly, our kauri forests are already at risk from kauri dieback, while wild goats and pigs, and in some places wild cattle, are adding to that pressure. We don't want another large-hooved animal like deer spreading soil and disease through our forests," he added.

Anyone who saw or heard wild deer was urged to call the 24/7 deer hotline 0800 FIND DEER (0800 346-333) immediately.

More information about feral deer is available at www.nrc.govt.nz/pestcontrolhub