The rabbits around Stanthorpe are in for a tough time as a project targeting their homes aims to reduce the pest animals’ impact on valuable crops and pastures.
Queensland Murray-Darling Committee (QMDC) Weed & Pest Technical Officer Shane Cartwright said the key was coordinated control but not just between landholders.
“We are also working at coordinating control methods so it’s not just ripping warrens or clearing harbours or removing blackberry or fumigating burrows; it’s got to be a combination of these things to have a significant impact on their numbers.”
The area at Stanthorpe targeted by the current project between landholders, QMDC, Biosecurity Queensland, the Darling Downs-Moreton Rabbit Board and Landcare spans both sides of the 116-year-old rabbit fence.
According to Darling Downs-Moreton Rabbit Board Inspector Mark Ridge, for every one rabbit on the “clean” side of the fence, there might be 10 or more on the dirty side.
“This places enormous pressure on the fence which is why we’re involved with this coordinated program, to try and establish a buffer zone on the ‘dirty’ side to reduce the threat to the fence which has obviously been doing a great job,” Mr Ridge said.
“If we can take away the rabbits’ harbour, there is more chance of them being picked up by predators before they make an attempt to cross over into the ‘clean side’.
“Removing their homes is a longer term solution; if the homes are left, rabbits have repeatedly proven they can quickly re-populate an area.”
For livestock manager Clint McErvale this is obvious as “Croyden Park”, a breeding and finishing operation in the Cottonvale district near Stanthorpe, spans both sides of the fence.
On the clean side, the focus is on removing old piles of dead wood and blackberries while on the dirty side, warren ripping about 90 sites has been added to the list.
“We currently only run about 120 head of Angus cross cattle on the 560 hectares (1400 acres) here because we made the decision to lighten the stocking rate to allow the pastures to rejuvenate,” Mr McErvale said.
However, he said the rabbit population on one side of the property had significantly hampered the effectiveness of this measure.
“The rabbits are really impeding our efforts so if we can control them, we will hopefully get some decent pasture regeneration,” Mr McErvale said.
“It’s hardly worth the effort if the rabbits continue to eat the pastures we’re trying to protect.”
To highlight the longevity of the issue, it’s believed some of the recently ripped burrows on “Croyden Park” have been around for more than 40 years.
Biosecurity Queensland senior zoologist Dr David Berman said work was underway to find out exactly what rabbits cost agricultural production but current figures indicated 100 rabbits could eat as much as a cow.
“We’re also working on how we calculate the number of rabbits in an area but currently, the calculation is that for every one rabbit you see using a spotlight in a one kilometre stretch, you multiply by 17 to get the figure per square kilometre,” Dr Berman said.
Ken and Sue Wilson “Eastlynne” Dalveen are hoping harbour control will allow them to boost herd numbers on their 400ha (1000 acre) property which is on the “clean” side of the rabbit fence.
The couple’s breeding operation, based around a mixed herd of mainly Charolais stock with some Murray Grey and Angus, could be expanded with the removal of old stacks of deadwood which have been on the property for years.
“We estimate we lose the ability to run about four head to the timber and another four are lost to the rabbits (eating pasture) so we’re looking at a substantial loss per year,” Mr Wilson said.
While Mr Wilson doesn’t believe the rabbit population can be eradicated, he certainly believes it can be controlled.
“Rabbit numbers are historically low here so we will never get a better chance to attack them in their harbours,” he said.
“This is a good year to burn safely because of the green grass and we can also burn while there is dew on the ground.”
Mr Wilson said he became involved in the control project because of the willingness of the project partners to help out.
“If everybody does a little bit, we can manage rabbit numbers.”
QMDC’s Shane Cartwright said the idea behind the joint project was to provide funding and assistance to allow groups of landholders to coordinate their efforts.
“While there is some impact from just one landholder taking action to control blackberry bushes – a favourite haunt for rabbits – the impact is exponentially greater when their neighbours are also working on control methods,” he said.
“While this project is limited to a few sites – some of the worst in the area – what we’re hoping is to prove how well this approach works and be able to go to other landholder groups with some solid facts and figures about not only the control costs but also the benefits.”
Mr Cartwright said the idea was to identify core infestations and target those with warren ripping to disrupt the breeding cycle and then remove other safe harbours which allowed predators to keep the numbers down.
Biosecurity Queensland, a part of the Department of Employment, Economic Development and Innovation, will focus their research on warren ripping during the next couple of years.
“The idea is to see if by knocking out key warrens, whether you can have a beneficial impact on controlling rabbits over a broad area,” Biosecurity Queensland senior zoologist Dr Dave Berman said.
“There is the potential that by removing the population on larger warrens, the smaller ones in the surrounding area may no longer be viable.”
Dr Berman said the aim was to provide landholders with the means to have the greatest impact while minimising spending.
“We want to make it as easy as possible for people to control rabbit populations.”
Dr Berman said while that was the overriding objective of current research, the relative importance of warrens when compared to log piles or blackberry bushes would also be investigated.
“The other part is to measure the benefits to biodiversity and agriculture when rabbit populations are controlled,” he said.
“On the site at Cottonvale which spans both sides of the rabbit fence, we have some early indications that numbers of macropods (wallabies and kangaroos), bandicoots, echidnas and native grasses are more prolific or even unique to the ‘clean’ side.
“Even at low densities, rabbits have a significant impact on native vegetation, native animals and livestock because it appears rabbits take out the best plants and parts of plants, depriving other animals of valuable micronutrients. They also change the composition of pasture so that there are more weeds and less of the palatable species.”
For more information on the range of pest and weed activities undertaken by QMDC, visit www.qmdc.org.au
April 2009.
Photograph: QMDC Weed & Pest Technical Officer Shane Cartwright, Darling Downs-Moreton Rabbit Board Inspector Mark Ridge and landholder Ken Wilson “Eastlynne” Dalveen hope removing harbours such as these log piles and blackberry bushes will give predators a fighting chance to keep rabbit numbers low.
