Gliders and barbed wire
‘There are confirmed records of five of the six Australian glider species becoming entangled in barbed wire. Only the Feathertail Glider seems to have escaped this fate. “It is ironic that attempts to promote the restoration of degraded woodland vegetation by fencing it off from livestock grazing may inadvertently negatively impact on wildlife such as gliders” Gliders of Australia, A Natural History. David Lindenmayer 2002.
Barbed wire has been recognised as a significant problem for gliders by the Wildlife Preservation Society of Queensland through their Glider Network (see below) and is listed as a threatening process in the recovery plans for the Yellow-bellied and Mahogany gliders.
Barbed wire fences are a problem for gliders when the distance between trees is greater than a single glide and there is a top strand of barbed wire in between that they don’t see, or lack the height to clear. A lot of photos of entangled gliders show the barbed wire up against a tree trunk or in a clearing. The clearing of wide areas along fence lines and presence of only shorter trees at the edge are significant problems. The distance they can glide is greatly reduced if the trees that remain are not tall enough to allow a long glide – too often they come in too low and the slightest contact with the sharp barbs entangles them. A Mahogany Glider for example, loses 1m in height for every 1.9m in distance it glides.
Note the vulnerability of those gliding membranes.
I have rescued hundreds of flying foxes off barbed wire fences, but was surprised recently to discover how difficult it was to untangle gliders – a Sugar Glider and a Greater Glider. They are much more difficult to hold securely, they squirm out of your hold more easily and their longer hair presents problems. It is difficult to get a good hold and untangle them when they are usually entangled close to the body. This combination makes it very difficult to get them off an intact fence compared to a flying fox. They are usually entangled on a wing bare of hair and at quite a distance from the body. The rescue of the Greater Glider necessitated cutting the fence, the first time I have ever had to do this.
This endangered Mahogany glider had two pouch young when she was caught on a barbed wire fence beside a farm gate.
Notice how unstable all three gliders are in these three photos. Entangled flying foxes can usually hang by their feet relatively comfortably, albeit in pain and weather as experienced by all species. In common with most wildlife though (birds, macropods, koalas) gliders must try to find a point of balance with minimal effort, while they hope for rescue.
The Queensland Glider Network (QGN) was established in early 2006 to support glider populations through communication, education, data collection, and mapping. QGN aims to raise awareness of gliders and their habitat requirements, and improve community knowledge, interest and support for gliders. They are a hub for glider conservation, research and information exchange in Queensland. Go to their website for the excellent pamphlet A Revegetation Guide to the gliders of south-east Queensland (April 2022) and much more.
Their advice for wildlife-safe fencing for gliders is post and rail fences or retrofit wire fences with high visibility additions (eg poly pipe or white tape) to the top strand. Gliders are especially vulnerable to entanglement on fences along watercourses or ridge lines or between stands of native vegetation. These movement corridors are priorities for wildlife-friendly fencing.
Greater glider entangled on a fence
Fencing injuries Mahogany gliders
The endangered Mahogany Glider is found only in coastal eucalypt woodland in far north Queensland. These animals rarely come into care but when they do it is usually because they have been injured on barbed wire. More than 30 of these endangered gliders have been found stranded on barbed wire. The lucky ones have been found alive and rescued in time for treatment and recovery. Over the last 25 years better treatment regimes have led to better recovery and returned of the injured gliders to their habitat.
Daryl Dickson and Geoff Moffatt from Mungarru Lodge Sanctuary, seen here clipping soft flat agricultural hose over the barbs at a Mahogany glider hotspot for entanglement. It has several benefits in that it is easy to use, protects the gliders from the barbs and it is highly visible.
They have worked with injured Mahogany Gliders for the last 25 years and learned that most can recover and be released with only minor, but diligent wound management. The gliding membrane tissue has remarkable recovery capacity as long as it is infection free. One of the most important parts of their recovery has been to recognize the level of fitness these animals require at release. They are athletes of the forest and they need a very large glider enclosure to ensure they can adapt to any changes caused by the injury to their recovered gliding membrane (patagium). It is essential that they build up strength and fitness that they may have lost while in care.
Read about their work with Mahogany gliders here.
After 10 years delivering projects to help endangered mahogany gliders, the Mahogany Glider Recovery Team have learnt a lot and built great partnerships to connect sections of glider habitat, manage woodlands, make grazing properties more glider-friendly, kickstart a population survey and monitoring program, and more. This latest video gives four practical tips for landholders in glider country, visitors to glider country and anyone with a soft spot for these tiny and unique creatures. Watch a 2023 video with 4 tips for landholders in glider country here.
Cassowary Coast Council has worked with Wildlife Queensland to develop signage to raise awareness of the dangers of barbed wire fencing for Mahogany gliders.
From the recovery plan for the Mahogany glider:
4.2.7 Barbed wire fencing
Evidence suggests that barbed wire fences (usually used to contain livestock) are a major contributor of fatality and injury of the Mahogany Glider as a result of entanglement (Jackson, 2000c; Parsons, 2005). Mortality occurs when the patagium of the gliders become entangled on the top barbed wire strand, causing them to become entwined. The glider then usually dies of dehydration after several days (Parsons & Latch, 2006). The impact of fences appears to be greatest in highly fragmented areas, where animals must regularly cross barbed wire fences to cross gaps in their habitat (van der Ree, 1999; Booth, 2006). Fences located on the edge of large gaps in habitat (more than 20 m) pose the greatest risk of entanglement because the gliders are more likely to land lower down when travelling across these gaps (Parsons & Latch, 2006)
Where landowners are reluctant to accept changes to fencing, gliders can be helped by stretching a bird wire ‘apron’ between the top and bottom strands at hotspots. The apron helps because if a glider strikes the apron section, it cannot spin around the top strand because of the wire-netting curtain. Instead, there is a good chance the glider will be able to clamber off the fence and either leap to the target tree or jump to the ground and scramble to the nearest tree. (Rupert Russell, Julattan)