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 kilometres 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 frontline 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."
Otago Regional Council (ORC) data backs up this statement. Using the Modified McLean Scale (MMS), which rates infestation based on signs of activity (from one to an extreme 10), night counts and inspections reveal more than 100,000ha of land in Otago, particularly Central Otago but also North Otago and coastal areas, are in breach of MMS 3, also referred to by the ORC as Maximum Allowable Level 3 (MAL 3).
At this level, rabbit sign is "infrequent, with buck heaps (faeces) more than 10m apart".
Indications are these levels could quickly rise.
"Basically, this year (2009-2010) has been an exceptional breeding year for rabbits with none of the usual rain," ORC regional services group manager Jeff Donaldson says.
"Last year's night count indicated that around all of our sites, rabbit numbers had increased - even on sites where control was a feature. The Upper Clutha and Lindis areas are of greatest concern, but also Cromwell, Alexandra, parts of Wanaka and Cardrona.
"The rise has been occurring over the past few years. A good breeding year on a property of level four is not going to be that noticeable, but a good breeding season of rabbits on a property with level of five-plus is going to create problems."
At the suggestion of a plague, Mr Donaldson preferred other words: "There is an emerging problem which has been identified. If we don't get a good poison take over winter, we are going to have a bigger problem next year."
Such is the concern, Federated Farmers last year requested the Government renew public funding of rabbit control. It was declined.
There is no question the illegal introduction of rabbit haemorrhagic disease (RHD) in 1997 drastically reduced numbers of the pest.
Such was its initial success - various properties recorded kill rates of more than 90 per cent - that some stopped traditional rabbit control methods such as poisoning and shooting.
Therein lies one reason for the recent rise. To take full advantage of RHD, property owners have long been advised to target survivors with "secondary" control methods.
Killing off those rabbits minimises the chance of immunity or genetic resistance developing among a community, allowing the next cycle of RHD to remain effective.
"A lot of people thought RHD was going to be the silver bullet," says Mr Linwood who, being a professional shooter, knows a lot about bullets.
"Well, I'm afraid it wasn't. And now they are going to find out [what happens] if they have not taken seriously the weather patterns in the last three to four years. There is no doubt that in pockets, in the past three to four years at least, they have increased. That is a reflection that RHD is not working to the level that it was.
"We are taking these breeding seasons very, very seriously. Normally, we don't start shooting until about now, but because there were so many rabbits looking for feed, we got stuck in before Christmas. We got the call to step up a gear - four gears actually. We are flat-out now, right through until November. They will stop breeding when it cools down. You know that every rabbit you get now and before spring is so important."
On Earnscleugh, rabbit control takes top priority, with about $60,000 to $70,000 spent a year on shooting.
Says Mr Campbell: "We can't farm with rabbits on it."
And he knows all about infestation. During the 1980s, Earnscleugh Station often featured in the media, with articles describing the hillsides "moving with rabbits".
According to the Lough report, approximately 14,000ha of Earnscleugh Station are recognised as highly (20 per cent) or extremely (80 per cent) rabbit prone.
However, vigilance has helped Earnscleugh reduce rabbit populations. Internal and boundary rabbit-proof fencing was erected to create manageable blocks and boundaries for control, though poison success rates of 70 per cent were lower than other properties, largely due to bait and poison shyness in the rabbit population.
That meant shooting became a key tool on Earnscleugh, as did good management practices such as keeping stock off land recently cleared of rabbits to allow a seed bank to build up over a number of years.
Scrub was removed to make areas less favourable to rabbits, while grass cover was increased to enhance the success of predators and the incidence of coccidiosis, a disease of the liver that can cause high mortality in young rabbits.
Notably, decline in rabbit populations was achieved prior to the arrival of RHD. The advent of RHD did help; allowed to spread naturally (rather than by biocide techniques such as injecting animals with the virus), it provided further assistance in maintaining the low rabbit levels.
Nowadays, Earnscleugh employs one fulltime rabbiter, Mr Linwood. The predominant secondary controls are night-shooting, day shooting with dogs and some helicopter shooting. No poison programmes have been used since 1995.
BUT let's go back to Conroy's Rd. The disparity in fences, some rabbit-proof, some clearly not, makes this place is a crossroad of sorts.
Mr Linwood says at certain times of the day one can watch rabbits stream from neighbouring properties, cross the dusty byway, and search for access to the more abundant feed on Earnscleugh Station "It just shows you how vulnerable properties - even Earnscleugh - are to outside control. There are a lot of access problems with public land; you've got to keep your fences up to scratch.
"It's great having access to public land but it is creating a lot of problems. You also have these block holders who have done nothing in the last three or four years. You can see how little feed is on there and, of course, these rabbits are looking for a place to go."
His boss, Mr Campbell, agrees: "The lifestyle blocks ... are a major problem. It is costing us a fortune in that Conroy's corner, trying to keep rabbits out of there.
"We don't want to open and shut a gate every time we go into our out-station, which is 20 times a day, so we have netted the road part-way in to try to stop them.
"I think it is the subdivision across the road that no-one is living in yet," Mr Campbell says.
"The problem is that no one seems to be doing anything about it. The Government doesn't seem to be enforcing anything."
Under the ORC's 2009 Regional Pest Management Strategy (RPMS), landowners are required to maintain properties to Maximum Allowable Level 3. Mr Donaldson: "If your property is impacting on your neighbours, we will be coming back to have a talk to you".
Responding to concerns expressed by some that a date for action of 2012 under the RPMS is "too late", Mr Donaldson points out that the ORC can currently enforce its strategy. "People need to have an approved management plan in place. "
Should a landholder not comply with an approved control programme, the ORC can issue a "notice of direction" or a "notice of required work" stating what the landholder is required to do and the time in which this must be achieved.
"One of the problems we have is that we work on complaints," Mr Donaldson explains. "Now, nobody complains about rabbits from a neighbour's property until they get hit hard [with rabbit infestation]. If people complained about that, more action would be carried out."
A growth in lifestyle blocks, vineyards and properties with absentee owners is contributing to the rabbit problem, Mr Donaldson says.
"Ten years ago, we didn't have so much subdivision; there were fewer properties to monitor ... If you've got a viticulture block of, say, 80ha, and you're using fertiliser and irrigating so you've got nice long grass and have rabbit-proof netting, you're not going to cause anybody a problem.
"But if you have a property that only uses half of the land and doesn't do anything with the other half, where the owner doesn't care about the rabbits - that is happening to a certain extent. People need to understand that they are responsible for controlling rabbits on all their land."
The problem is, effective rabbit control comes with a hefty price tag.
On some stations where aerial drops of 1080 are required, the cost can exceed $100 per hectare. On a 20,000ha station that equates to a bill of $2 million.
No wonder, then, there were a few celebratory drinks when RHD started killing rabbits en masse.
However, Mr Donaldson believes the initial success of the virus was more good luck than good management. "Some rabbits were captured and injected.
When the rabbits died, they all thought they had died from the virus, but in some cases they were dying from blood poisoning."
For every one live dose that got through the system, there were others that unintentionally became part of an RHD vaccination programme.
"That was always a problem for us and we told the Government that - if it didn't come in legally it would come in illegally and it would not be managed well. In saying that, there was an epidemic. It went through. It killed a load of rabbits. It is still there and is a reasonable tool.
Though immunity to RHD is an issue, Mr Donaldson sees a solution: killing the survivors by other means lessens the risk of that immunity or genetic resistance spreading.
"If the population is going up, it is because the virus is not working. But you can go in and poison and reset the population. Obviously, not back to zero, but you will collect a lot of those immune rabbits.
"We can't control RHD; it is out there in the environment and it's not mutating to the extent that it is going to be so different in five years' time ... what we are looking at is perhaps whether there is an ability to boost the virility of the virus in the future."
- OTAGO DAILY TIMES
'BRING IN AUSSIE FLEAS'
The farmer whose property was at the centre of a biosecurity ruckus in August 1997 after a deadly rabbit virus was released now wants another killer disease liberated.
Donald Young is urging the release of myxomatosis.
He has had some Australians ("friends of a cousin") staying at his Lowburn property recently.
And you get the feeling he wouldn't mind a few more. Particularly if they were rabbits, which had fleas, which carried the disease.
Myxomatosis has been tried before in New Zealand, back in the 1950s, but it failed because it lacked a means to be spread from rabbit to rabbit. Specifically, it requires the European flea, an insect the Australian rabbits have but which ours don't.
"There is not much point in pussy-footing around," Mr Young says.
"If we could only get myxomatosis going ... but, of course, nobody has got the guts in local bodies to force the issue.
"RHD was, in a sense, easy because it is a virus that spreads easily, whereas myxomatosis, also a virus, needs a vector. The easiest way would be to get a container-load of Australian rabbits already loaded with fleas."
Mr Young concedes his idea is contentious. "You've got to sell it to the green element. Those who grizzle most about 1080 you'd expect wouldn't like myxomatosis.
"Somebody has got to bite the bullet ... Those West Australian people said they don't have much of a rabbit problem now."
However, ORC regional services group manager Jeff Donaldson doesn't think much of the idea.
"I don't think we would ever bring in rabbits as well as the rabbit flea," he says.
"You would have to put them into quarantine because you wouldn't know what other diseases they had. They've got blue tongue and other things over there which would impact on what we could do ... We need to know that whatever we do is not going to impact on anything in New Zealand.
"We need to know there will be no mutation of the disease."
Back to the present. Mr Young is worried. If RHD doesn't knock back rabbit numbers this winter, "this time next year could be a concern".
"We were in this situation 11 or 12 years ago, prior to RHD coming in. We were in an impossible position. Things haven't really improved a hell of a lot. RHD was probably better than 90 per cent effective, initially. We had marvellous control. Two years ago numbers were getting up, but not as bad as now."
The Lowburn farmer has turned his back on rabbits for much of this week. He has been fishing, swapping the backdrop of brown tussock for the deep green foliage of the West Coast.
A place where you can scan the sea and contemplate what lies beyond the horizon.
Australia. Fleas. Plague.
