Otago Rabbit Control

Rabbits are not going away any time soon. They are an increasing problem in Central Otago as more rabbits develop an immunity to RHD. We hear about how farmer Bruce Jolly is controlling rabbits, and an overview from the Otago Regional Council.

Peter Preston has been working in rabbit control since the 1970s. Bruce Jolly is very proactive in controlling rabbits and does a pretty good job, and he’s had a history of bad rabbit problems on the property.

A regional overview of what is happening with rabbits in Otago with Peter Preston:

Rabbit numbers are up and down, and immunity to Rabbit Haemorrhagic Disease (RHD) is increasing. There have been some good runs of RHD this year which have controlled a fair few rabbits.

120 tonnes of carrots were used to bait rabbits last year, and Peter thinks about the same maybe used again this year.

He says the Council has a new pest management strategy coming into effect, but it might not be in place in time to have much effect on control this year. The new strategy is changing the level at which farmers are required to control rabbits.

The way to count rabbit infestations is on the Modified McLean Scale, which ranges from 1 for no sign and no rabbits to 8 for very frequent, and in large numbers and lots of sign.

Currently farmers only have to control rabbits when the number 5 on the scale is reached. This is defined as “sign very frequent with faecal pellet heaps often less than 5m apart in pockets and rabbits spreading.” Peter says this is where you see 10 to 20 rabbits spreading out of a gully, with obvious warrens and tracks, and the ground is bare.

Under the new strategy this is going down to the number 3 on the scale, which is “sign infrequent with faecal pellet heaps more than 10m apart, odd rabbits may be seen.” This is down to where you only see one or two rabbits he says.

Farmers have to pay 100% of the control costs, and Peter says aerial poisoning work may cost up to $100/ha, so it’s pretty expensive.

Most farmers do the work voluntarily, and the season for rabbit control is July to September. He says before the climate warmed up, they used to start rabbit control in about May.

So with the changing climate, there’s a very short season for rabbit control using poison, before farmers need the ground back for grazing in spring.

Central Otago is still the most rabbit prone area in the country, with very bad rabbit problems historically too. Just after RHD was introduced, numbers dropped to very low levels, but now the control work is escalating again.

They are monitoring RHD levels in rabbit blood, and finding that immunity levels are quite high, which means RHD is not as effective as it used to be, so more and more poisoning is required to keep numbers under control.

Peter says some rabbit control programmes have been very costly and the most expensive one he knows was five years ago near Wanaka which cost $90,000.

He says the Otago Regional Council doesn’t do complete monitoring of rabbits across the region, instead they look at numbers in historically bad areas and when landowners complain.

In Otago the farmers have to pay 100% of the costs of rabbit control. They can use any contractor, including the ORC to carry out control work.

The cost of carrying out control work is increasing he says, and many farmers want taxpayer money to be used to help them control rabbits.

There aren’t any other biological controls to use.

Most high country farmers have a fairly good level of understanding about control, but the amount they can put into it very much depends on product prices.

Peter says it’s going to be more expensive for farmers to keep the rabbits at level 3 on the Modified McLean scale.

Reducing rabbit levels is a good thing to do but it will take a lot of work. But keeping a lid on them means you don’t have to use poison, which is now a reasonably dirty word, he says.

At low numbers you can avoid having to use toxins on your property.

But he’s not worried about the current rabbit numbers, and says control will have to be constant and on-going. “Rabbits are not going away any time soon.”

Control of rabbits will be a constant, on-going battle, just like controlling weeds or putting on fertiliser. It’s another job that needs to be done and done properly, he says.

Two farms which have done extremely well in controlling rabbits are Galloway Station and Ernscleugh Station, both of which now have extremely low numbers. It just takes commitment, Peter says.

Interview with Bruce Jolly:

Ardgour Station is north-facing sunny warm country – just what rabbits like. It is 3600ha of freehold land. There is a small area of irrigated valley floors, 1000ha of arable flats which is dryland, and the rest is hill country.

The farm runs virtually all Merinos with a few cattle, with 9000 to 10,000 stock units. Numbers have been higher and lower at times, but with the drought and rabbit numbers, the current stock numbers are the lowest for quite a few years.

Ardgour is a family business with Bruce and his children. Bruce’s father owned the farm before him, buying it in 1954. Bruce has managed the farm since 1984, and increased his ownership by buying other family members out.

In the 1990s when Government phased out any inputs into rabbit control we were basically on our own.

Most rabbit prone areas got funding for only five years – as an incentive to make changes rather than relying on poisoning every year. This included a shared contribution to rabbit fences, and whole property plans were developed at that time. We have one of these.

Until then we would poison a third of the property every year, and it was very expensive. Poisoning worked but then we started getting periods where poison wouldn’t work any more, and the rabbits wouldn’t take the bait. It was always compromising stock management on the farm.

Having such large areas that we couldn’t graze at certain times of the year was difficult to work around. Then rabbit proof fences were put up – the hill country was divided into rabbit blocks. That meant one area could be poisoned and it wouldn’t be re-contaminated by rabbits.

That worked quite well, and it coincided with the wettest decade. The rain helped to keep numbers low due to deaths in the nest and generally poor conditions for rabbits to survive. So that work may not have been as effective as one may have though just looking at the rabbit numbers and the fencing.

Then just before RHD rabbit numbers built up significantly again, and I was about due to do a significant poisoning programme on the hills. As well we shoot 15,000 to 20,000 rabbits are year on the flatter areas of the farm.

And on the steeper country once a year we use shooters from a helicopter. But we stop that if they are shooting too many per hour and get it poisoned instead.

Now we have areas of the farm which are well controlled, and some parts which are fenced have had no poisoning programmes for 20 years. It makes a big difference.

Then we have other areas where we really are struggling to keep control. We’ve been doing a series of poison operations in the last three years. The area we did three years ago is starting to build up again.

RHD was fantastic, it decimated the population, and let the land recover. Some of the more fragile lower altitude country takes about 10 years to recover.

Bruce says RHD has changed the dynamics of the rabbit population and now it is harder to determine the stage where poisoning is required. The rabbits behave and live differently compared to before, and keep more in communities, which are very concentrated. Some of these areas are at level 8 on the McLean scale, and others on the farm are only at 2-3.

In the last financial year Bruce spent $45,000 on rabbit control.

He says his farming system would collapse without a rabbit management plan.

Last year he planned a big poisoning operation but found that RHD had knocked down numbers – it was probably the best knockdown since the original introduction, and over a very big area.

This meant he halved the area he had planned to poison. About a third of his farm has a potentially very bad problem if not controlled. Numbers of rabbits can jump up to 6-7 on the McLean scale within six months if not controlled.

A group of farmers from Marlborough want a return to rabbit boards and more taxpayer support for rabbit control, but at the moment rabbit control is 100% user pays.

Bruce says in his view rabbit control is not just a farm economic issue, it is an environmental issue.

He says it’s hard to keep it all equitable. His rabbit prone country can only support 0.2stock units/ha, but would cost around $20/ha to control for rabbits, which is much more than any returns from that land.