By Melissa Coleman
Despite more and more cluster fences popping up in the Southern Downs region, very little research into the effects on Australia’s native marsupials has been recorded.
Over the last decade, graziers have erected more than 700 robust fences to keep wild dogs away from their livestock in Queensland.
Yet, while graziers report significant increases in livestock survival rates, the impact on native Australian animals, including endangered species, is still unclear.
Dr Ben Allen from UniSQ is a wildlife ecologist whose job is to explore practical solutions to large-scale ecological problems associated with balancing the needs of wildlife with those of humans.
Since 2012 Dr Allen and his colleague Dr Deane Smith have been investigating how well cluster fences work.
Dr Allen said their research targets the ecological process of competition and over-grazing, and predation associated with cluster fencing.
“We don’t have a lot of data for all potential interactions, but all are worthy of investigation.”
“Cluster fencing is being erected at a rapid rate which is a problem for science because it’s hard to keep up. It comes down to the possible and the probable.”
“People assume there will be a benefit with no dogs and no kangaroos, but all the fence enables is better management.
“There is a strong case to develop adjustments to the fences that will allow free movement of threatened native species while continuing to keep predators out,” Dr Allen said.
The two scientists have collected empirical evidence and are the only researchers in Queensland and New South Wales gathering information on the movement of predators, competition for food, the impeded movement of native animals, and the impact of cluster fencing on the native macropods and the environment.
“Predation effects occur where wild dogs kill and eat grazing animals, and the competition effect is when kangaroos compete with sheep or cattle for food,” Dr Allen said.
“The purpose of the fencing is to reduce that competition and to reduce predation.”
“In general terms, the net effect is that Australia’s marsupials are doing well.”
“In the places where we have done this work, we haven’t found any suggestions such as inbreeding causing disease or marsupials unable to migrate. Both of these things are good news for threatened species.”
Comparisons between areas inside cluster fences and areas that are ‘outside’ reveal there are hundreds of kilometres squared of land.
“At the scale these properties are operating, there is so much movement still happening that you don’t get that inbred style of effects.”
However, part of the research showed that one of the biggest problems for macropods is hydatid tapeworm which can be passed onto kangaroos by wild dogs.
Dogs can host several thousand adult tapeworms in their intestine, and when the tapeworm eggs are passed in the dog’s faeces, they survive in soil and grass for several months.
Animals such as sheep, cattle, goats, pigs, horses, kangaroos, wombats and wallabies can become infected by eating grass contaminated with eggs.
“This type of predator and prey mingle keeps the tapeworm going, but when you put up a fence and get rid of the dogs, it breaks the cycle of tapeworm, and the macropod population receives a natural worming.” Dr Allen said.
“Their digestibility and lung capacity improves in leaps and bounds; those things hampered by handfuls of worms are now no longer hampered, and so on an individual level, they are healthier.”
“At a population level, when you consider the whole region, kangaroos do really well out of cluster fencing because you’ve effectively taken away their biggest enemy.”
The research suggests that all macropods either do as well or better in places where their biggest risk factor, wild dogs, is eliminated.
“On an individual level, they might be impeded by the fencing, but the bigger picture is that there is no harm to the macropods at all through that fencing.”
“However, where you might get declines in kangaroo levels in fencing is when a farmer facilitates the elimination of kangaroos,” he said.
Most farmers consider kangaroos a pest because livestock must compete for food and when kangaroos are on the inside of their fence, that’s when graziers must decide whether or not to get a permit and eradicate them.
Despite the ongoing study into macropods, Dr Allen laments that no one has done any study on the effect on koalas in the region.
However, in Dr Allen’s opinion, he believes that their number one problem is tree clearing, then wild dogs and disease.
“We talk a lot about diseases such as chlamydia, but if you’re ranking problems, then tree clearing is a stand out at no. 1; the next biggest problem is wild dogs, then disease.”
Another common issue raised in the cluster fence debate is whether humans are sabotaging the ecological system.
“We are working with an altered landscape already. There’s much scientific support for the argument that all of those alterations have actually made kangaroos more abundant,” Dr Allen said.
“Effectively, we have made a haven for kangaroos, dogs and rabbits because we have cleared the land, grass has grown, and we’ve put in water troughs,” he said.
But a warning comes with this – For every intervention, there are going to be winners and losers.
Dr Allen said if you’re going to fiddle with something by putting up a fence or clearing land or putting in a water point, there is going to be winners and losers.
“In this case, the losers are the wild dogs and potentially kangaroos within the fences.”
Cluster fences have started appearing in western New South Wales and around Burke, Cobar, Wilcannia, and Mildura.
