The TBfree programme’s goal of eradicating TB in wildlife by 2040 is delivered through targeted possum control and wildlife surveillance. Eradicating the disease relies on strong community engagement and liaison with landowners and land users affected by operational activities.

Over 20,000 possums have been removed from the area since work began. Possums need to be kept to low numbers over multiple years to eradicate the disease.

Mount Allan aerial control

We’re running an aerial possum control operation in the Mount Allan area. While warning signs are in place, dogs should be kept on a lead and muzzled if in the area.

Mount Cargill ground control

Targeted possum control and a ferret survey are continuing in this area. Dogs should be kept on a lead while warnings signs are in place.

OSPRI-HALO Project Collaboration

OSPRI is excited to be working with the Halo Project to support establishing a long-term volunteer possum-trapping network in urban communities in Dunedin.

Information for pet owners

There are strict safety, quality assurance and monitoring requirements for the use of pest control techniques. The toxins used pose an extremely low poisoning risk to pets. To minimise primary poisoning, bait will be in bait stations or bags, and there will be no toxins or traps within 30 metres of, or in sight of tracks. The toxins are slow-acting and dogs would need to eat a number of carcasses (possums or rats) to be affected.

Due to the use of toxins, dog owners should keep their dogs on a lead in the area while warning signs are in place. If you think your pet has been poisoned, contact your local vet for help or advice.

For more information on where to walk your dog, visit the Dunedin City Council website. You can call OSPRI’s Dunedin Office on 03 477 9829 if you're interested in a free dog muzzle.

Cats are not targeted in OSPRI operations. Toxins are not attractive to cats. However, trapping will be used in places, so we recommend keeping cats away from possum control operational areas.

Why is OSPRI undertaking possum control?

All cattle and deer herds around Dunedin are clear of TB. This is great progress considering there have been 7 herd infections since 2015.

Possums are the main transmitters of TB from wildlife to farmed cattle and deer. When herds in the area first became infected, wildlife surveys found infected possums around Mount Cargill.

To stop TB spreading, we need to keep possum numbers low for a number of years. We have completed ground-based possum control in parts of the Mount Cargill TB Management Area, and this work will continue in 2022.

Biodiversity benefits

Possums eat native plants and are a major predator of our native birds, preying on eggs and chicks. By keeping possum numbers low with targeted pest control, native wildlife and bush get a chance to thrive.

Large-scale pest control also benefits native wildlife. However, kākā are present around Dunedin and may access bait stations. Careful consideration is given to the methods used in any possible kākā habitat.

As well as working with the Halo Project in urban areas, OSPRI is collaborating with other Predator Free Dunedin partners to develop a succession plan that ensures the gains made by TB control work continue beyond TB eradication.

Methodology

All methods comply with animal welfare regulations and all methods require landowner permission.

Where live capture traps are used, contractors must check these daily. No traps will be placed within 30 metres of, or within sight of public tracks.

Toxins include Feratox in bait bags. No bait will be placed within 30 metres of, or within sight of public tracks.

Challenges

The operations around Dunedin involve a wide variety of terrain, from urban areas to rural farmland, forest and scrub — both flat and mountainous. The damp coastal vegetation hosts high numbers of possums.

Possums aren’t the only ones using the area. The TB management area is on the city’s doorstep and hosts large numbers of dog walkers, trampers and mountain bikers. The balance between the efficacy and cost of control methods, and the needs of recreational users is an important part of discussions with landowners.

Research papers

Cost-effective control of TB in the Northern South Island High Country (NSIHC): Identifying the habitats and vector species requiring control — (R-80629) Byrom A, Nugent G, Yockney I, Poutu N, Whitford J, McKenzie J, Shepherd J, Porphyre T 2007. LC0708/033. 85p.

Spatial prediction of brushtail possum (Trichosurus vulpecula) distribution using a combination of remotely sensed and field-observed environmental data — Porphyre, T., McKenzie, J., Byrom, A. E., Nugent, G., Shepherd, J., & Yockney, I. 2014. Wildlife Research, 40(7), 578-587.

Reduced spillover transmission of Mycobacterium bovis to feral pigs (Sus scrofa) in New Zealand following population control of brushtail possums (Trichosurus vulpecula) — Nugent, G.; Whitford, J. Yockney, I.J.; Cross, M.L. 2012. Epidemiology and Infection 140: 1036–1047.

Relative utility of TB hosts as sentinels for detecting TB — Nugent, G.; Whitford, J. 2008. Animal Health Board Project No. R-10652. Landcare Research Contract Report: LC0708/032. 38