Wildlife fencing injuries
86% of entangled flying/gliding nocturnal wildlife are caught on the top strand of barbed wire fences, and 95% on the top two strands. Barbed wire is recognised as a threat in the recovery plans of a number of species including the Spectacled and Grey-Headed flying-foxes, the Mahogany and Yellow-bellied gliders. An animal in flight is likely scanning the distance, not focusing on close-up objects. Trees are obvious obstacles, but thin strands of wire fence are not readily seen at night. The resulting injuries from vary greatly depending on a number of factors:
- how long they’ve been on the fence – they do more damage in trying to free themselves – ultimately dying from starvation and dehydration
- the weather – has the animal been in full sun or very cold or wet weather
- the force with which the animal has hit the fence and so spun around vertically and/or horizontally. The tightness around the barbs results in loss of circulation and a greater chance of die back of glider and bat membranes.
- how many points the animal is caught on the barbs
- whether the animal resorts to trying to bite itself off the fence and so inflict mouth/palate damage which can be severe to to the point of fractured jaws
- presence of predators
- introduction of infection
- entanglement on the body, as opposed to the wings/membranes, can result in the protrusion of abdominal organs
Injuries from other fence types and terrestrial animals are similar, though animals that get hung up in fences eg macropods, emus, experience traction injuries at the hip and other joints.
Fencing injury hotspots
Hotspots for entanglement include ridge lines, near feed trees, new fences, fences across/near water where flying foxes come to drink.
Hotspot: fence bordering water where bats come to drink, note the black polypipe of the top strand
Overgrown fences avoid entanglement. This becomes one of our hotspot fences on a ridge line when the grass is cut after the wet season.
Hotspot: we recommend that only low shrubs are planted beside security fences. Feed trees near barbed wire fences in paddock are a similar hotspot as bats lose height as they initially leave the tree.
Maintain your barbed wire fences
A lot of harm is done to wildlife by fences that are no longer functional or necessary.
Wildlife and barbed wire – Greater Shepparton City Council Australia
How Mending Fences Makes a Difference for Migrating Big Game USA
