Satellites reveal the underground lifestyle of wombats

The furry marsupials have proven difficult to study in the past because of their nocturnal lifestyle and underground homes that are often in remote parts of Australia.

However, a combination of high-resolution satellite imagery and remote motion-activated cameras is helping South Australian researchers compile the first species-wide mapping of distribution and abundance of the Southern Hairy-Nosed Wombat.

There are three species of wombats: the Southern Hairy-Nosed, Common and Northern Hairy-Nosed Wombat.

While the Common Wombat battles a serious mange outbreak and the Northern-Hairy-Nosed recovers from a brush with extinction 20 years ago, the Southern Hairy-Nosed Wombat is thriving with the population estimated at more than one million.

This has prompted Mike Swinbourne from the University of Adelaide’s School of Biological Sciences to harness the latest technologies to quantify their numbers.

“I’ve essentially tracked how the population of Southern Hairy-Nosed Wombats has changed since European settlement and I am looking at the impact in the future of things like climate change and land use change,” he said.

Swinbourne said while field trips into the harsh Australian Outback were still conducted, it was the availability of high-resolution satellite imagery capable of collecting images with a ground resolution of less than 0.5metres that had made the study possible.

The PhD candidate said wombat burrows were clearly visible on modern satellite pictures, giving him a starting point for the count without leaving his desk.

“We can use Google Earth, Google Maps and other satellite tools to search whole regions whereas in the old days you’d have to walk the ground – some places were inaccessible so you could never get to them or you’d have to pay for aircraft to fly over, which was prohibitively expensive,” Swinbourne said.

“We’ve been trying to work out how many wombats there might be per burrow and that’s where the motion activated cameras come in.

“We’ve installed them outside warrens all across the country to find out what the wombats are doing, how many animals are using a burrow at any one time or how often they are used.

“It varies completely – some burrows are only used one night a week while others are occupied every night and sometimes by multiple wombats.

“Then we can count how many burrows there are, do the calculation, and that gives us a pretty good estimate of the size of the population – there’s about 0.4 wombats per active burrow.”

Swinbourne has also utilised ground penetrating radar, which is more typically used for geophysical research, to map the underground burrows of wombats without disturbing them.

He said this had shown some burrows to be complex networks with multiple chambers and a labyrinth of interconnecting tunnels.

“In the past the only way to do that apart from crawling inside, which is not a good idea, was to dig them up.

“But a large percentage of the wombat population lives in regions where the ground is hardened layers of calcrete limestone it’s like sheets of concrete and you can’t dig it up so no one’s been able to look underneath those before.”

Swinbourne is presenting his research at this week’s three-day Wombats Through Time and Space conference (https://www.adelaide.edu.au/environment/wombat-conference/), the biggest meeting of wombat experts in 20 years.

South Australia is home to 90 per cent of Southern Hairy-Nosed Wombats, which Swinbourne predicts have reached their highest numbers since the introduction of destructive European rabbits to Australia in the late 19th Century.

Adelaide, the South Australian capital, isl hosting the September 17-19 conference, which features more than 60 delegates and 35 speakers ranging from researchers, zookeepers, wombat carers and farmers.

Wombats and koalas share a common ancestor called the Diprotodon – the largest known marsupial – that was bigger than a cow and roamed Australia approximately 1.6 million and 45,000 years ago. The modern wombat is similar in stature to a solidly built medium-sized dog and has cubed-shaped droppings.

“Wombats have been here almost forever but no one really started to study them in depth until the 1970s,” Swinbourne said.

“There’s still a great deal we need to learn but we’ve really started to ramp up the research recently because we now have these tools we didn’t have in the past.”

Andrew Spence is senior jouirnalist with The Lead South Australia news service (http://theleadsouthaustralia.com.au) from which this article has been republished under a Creative Commons Attribution 4.0 International License