Sustainable farming - possums

Written by Dr Clive Dalton

In a nutshell...

The Australian Brushtail Possum (Trichosorus vulpecula) was introduced into New Zealand in the late 1800s to establish an export fur trade.
Only 200-300 animals were released in about 20 locations and now the population is quoted as 70 million.
The exercise was an ecological disaster and there is no way New Zealand will ever eliminate the possum. Control is the only hope.
Possums kill native wildlife (young birds and eggs) and are vectors (carriers) of bovine tuberculosis which is an enormous threat to our meat and dairy exports.
At present, only a small proportion of possums carry Tb, but they can also spread it to other wild vectors such as stoats, weasels, pigs and deer.
The fear is that infected possums will spread Tb to non-infected possums (eg. in Northland) and this will incorporate other wildlife to make control difficult and expensive.
Control at present means use of traps, shooting and poison (cyanide and 1080).
Use of 1080 is most popular but is a highly contentious issue among conservationists, farmers, Forest and Bird members and politicians.
Greatest hope for a solution lies with genetic engineering a means of controlling their fertility.

Severe defoliation of trees in the bush, especially Northern Rata.
Dead trees (especially Northern Rata) in the bush canopy - clearly visible from the air.
Fruit trees in gardens being robbed at nights.
Possum dung pellets around trees bearing fruit or flowers.
Rubbish bins being searched for fruit.
The spring buds on roses being eaten with fur left on the thorns.
Many possums seen on pastures and in the trees at night.
Tb infected possums being found (showing cheesy lymph nodes under arms and back legs).
Possums hissing and squawking at night and running over the roof.
Clear tracks from the bush into the paddocks. Fur on the fence wire.
Sick (dopey) possums seen out in the paddocks during daytime.

Regeneration of native bush, and no dead trees in the canopy.
Possums not doing damage in gardens.
No sign or sound of possums near dwellings.
Control and reduction of Tb endemic areas.
No new outbreaks of Tb in Tb-clear areas.
Stock owners carrying out all requirements of the Animal Health Board for Tb control and prevention.

Make sure all cattle and deer on the farm are Tb tested when requested by AgrQuality who are contractors to MAF.
Before moving stock off the property make sure all documentation and tagging has been done. Each bovine animal must carry two tags.
Before moving stock away to another farm for grazing, check the Tb status of the farm they are going to. Check with AgriQuality for this information.
When stock come back from grazing, check with AgriQuality about when tests are needed. They may have to be tested before they come home.
Do not purchase stock or have them delivered to your property without the correct documentation. Check with AgriQuality.
Make sure AgiQuality know about all cattle and deer on your property.
Control possums on your property and co-operate with neighbours who are doing likewise.
Report any sick or dopey possum to AgrQuality without delay- and do not touch it incase it has Tb.
Take great care when using poisons that they are used correctly with minimal risk to other animals (domestic or wild). Document any poisons purchased and where used.
You need a license to use a firearm. Make sure your legal obligations have been covered.
There are a wide range of possum traps. Use one which is humane and cannot catch other animals. Jaw traps if used should be fixed on a tree well off the ground.