No longer on the run

Weather conditions, human activity (or a lack of it, in some cases) and a pest's increasing immunity to disease are keeping Central Otago farmers on their guard. The issue? Rabbits ... again. Shane Gilchrist reports.

Several kilometers southeast of Alexandra, on a sweeping bend around which users of State Highway 8 can enjoy the blue on blue reflections of sky meeting the waters of Butcher's Dam, there is Conroy's Rd.

Snaking away from the main drag, it is a handy shortcut to the orchards and vineyards of Earnscleugh, providing one doesn't mind coating a vehicle in Central Otago dust.

Take it slowly, allow the dirt to dissipate on the wind, and scan the fences to either side. To the northeast, closer to the highway, the strands of wire are spaced several inches apart.

To the southwest, though, the gaps between the heavy gauges are filled with netting; tightly bound, it disappears into the ground. It's a rabbit-proof barrier.

You see, for some, this road serves other purposes. It is both an indication of boundaries and the front line in an ongoing battle on the rocky peaks and gullies of Earnscleugh Station, a merino and cattle enterprise that encompasses more than 21,000ha, stretches from Fruitlands to halfway along the Cromwell Gorge and dominates the view south and west of Alexandra.

Mountain ranges aside, other things loom large around these parts.

"There is a rabbit plague on the horizon."Alistair Campbell, owner of Earnscleugh Station, minces no words. Nor does his rabbiter of the past seven years, Bill Linwood: "Ten rabbits quickly become 100; 100 quickly turn into 1000." And so on. All the more need, then, for the scoped and silenced .22 Ruger he cradles among the schist tors, just beyond that rabbit-proof fence.

The weather isn't helping. Not enough precipitation. Which is unfortunate, given rabbits and rain don't mix: deluges can flood burrows; long, dewy grass leads to deaths through disease; and grass growth offers better cover for predators such as cats and ferrets. For the past three years, spring has been dry and the winters kind.

According to a report commissioned by Biosecurity New Zealand (MAF) and released late last year, the operational window for 1080 poisoning - a key tenet in regional council-organised pest control - is now less than two months. The winters have been generally warmer and the grass palatable well into winter.

Poisoning in Otago used to start in late May; now it is typically well into July before the proportion of rabbits eating carrot bait is sufficient for poisoning to start. Warmer late-winter temperatures have prompted earlier grass growth. And when there is sufficient fresh grass, rabbits no longer eat carrot bait.

"If recent weather patterns continue, primary poisoning, particularly by aerial application, may no longer be a reliable fall-back," suggests the report's author, Roger Lough, who later states: "It must be stressed that there are many properties where rabbit populations have increased in recent years."