Low-cost fencing as a possum barrier–not a cost barrier

Differing types of predator excluder fences have been trialled over the years. While many are very effective at keeping out four-legged foes, the cost of building such fences is off-putting if not prohibitive. 

Zero Invasive Predators (ZIP) is an organisation developing and trialling innovations to help us find cost-effective tools for predator control and reinvasion prevention. A draft report on findings from a trial of a low-cost possum aversion fence, mimicking a fence built by OPBG Trustee Brendon Cross, showed promising results. 

In ZIP’s trial, a 0.9m high stock fence with rabbit mesh and three single hotwires was shaped to create a 20m2 pen. Then eight female and eight male possums were individually released and filmed, and the footage used to analyse how each one interacted with the fence. 

Despite high motivation to escape a small enclosure, close to two-thirds of the possums were contained by the fence. With only just over one third of possums (mainly males) escaping when highly motivated, it’s predicted that in practice, the fence will dissuade a higher proportion of possums from jumping it. 

Determining that fewer females managed to breech the fence, possibly because they did not jump as high as the males did on their first attempt, is welcome news. If this result is repeated in the field, it would effectively slow the reestablishment rate of possum populations in a cleared area. 

In the draft report, ZIP makes recommendations for further fence modifications to reduce the level of fence-jumping. 

It’s important that there are low-cost and practical options available to landowners, organisations and agencies that help slow down possum reinvasion in areas cleared of predators. Only then will options be suitable for landscape scale applications. 

In future, a similar design could be widely adopted in all farming sectors and beyond…