Farm fences are a fact of life. No one wants to hit an angry bull at 100 km/h. However, while fences are necessary to protect both motorists and livestock they also need to allow wildlife to move freely in order to feed, find mates and exchange gossip.
As a veterinarian I have seen many fence injuries. A lot of these involved kangaroos presumably trying to leap over the fence that caught their feet between the top two strands. The strands twisted around the kangaroo’s feet and held them fast. The more the kangaroo struggled, the more the wire cut into the limb. Eventually a farmer, member of the public or wildlife carer would find the kangaroo and cut it out of the fence. If it hadn’t been in the fence for too long the chances of recovery were reasonable. Unfortunately many of these animals were hanging for 24 hours or more, before they are found. By this time the constant struggles resulted in a massive build up of lactic acid in the hindleg muscles, which lead to capture myopathy. Even if myopathy had not occurred the pressure of the wire acted like a tourniquet severing or compressing the tendons and blood vessels supplying the foot. What looked to be a minor cut through the skin would eventually lead to the death of the limb and with it the kangaroo.
Apart from kangaroos I have also seen a lot of flying foxes and various gliders wrapped up in fences. I have come across the occasional kookaburra or other bird species, but they are not as common as the mammals. Presumably they don’t see the strands when they fly or glide and become tangled the way kangaroos do. In their cases they are usually wrapped up by the wings or gliding membranes. As these structures are quite elastic they are difficult to repair and the individuals often end up with permanent holes. If these are small enough the animal can be rehabilitated and released. Otherwise euthanasia is necessary.
The vast majority of these individuals, especially the gliding and flying ones, are caught on barbed wire fences. Were they to crash into a non-barbed strand they would be more likely to bounce off and fly away. Unfortunately the barbs catch in the skin and the struggle to get free only hooks them into the fence more completely.
After our fences were burned in the Black Saturday fires we decided to do away with barbed wire and replaced it with plain strands. I frequently see the local kangaroos sharing the paddock with the horses, as they are able to pass through the fence by going under or between the strands without fear of being snagged by the barbs.
If you are also concerned about the possible negative effects your fences could be having on the local wildlife assistance may be at hand. A group called Wildlife Friendly Fencing provides practical advice on how to keep your livestock in and your wildlife tangle free by using plain strands instead of barbs, covering hire risk areas with plastic piping to make the fence more visible, or using electric fencing. Check out their website at http://wildlifefriendlyfencing.com/WFF/Home.html). Your bats, roos, gliders, and birds will be glad you did.
Dr. F. Bunny