Counting wombats without ever sighting one

By Lauren White

Wombat

The northern hairy-nosed wombat. Credit: EHP

The northern hairy-nosed wombat (Lasiorhinus krefftii) is a very elusive creature. They are only found at one site in Australia: Epping Forest National Park in North Queensland. Highly endangered, wombat numbers were as low as 40 individuals in the 1980’s. They are very difficult to sight because of their nocturnal nature and largely subterranean lifestyle. They live underground in extensive burrows with multiple entrances, only emerging for a few hours each night. Sighting enough to get an accurate population count, which is important for the management of this iconic species, is almost impossible.

Trapping would allow a more accurate population count but is not ideal. It is labour intensive, difficult and can negatively affect the health of the trapped animals. It is also not very effective. Cages are set at the entrance to the burrow but wombats have been known to simply dig themselves under or around them!

Burrow Lauren

Some of the burrow entrances are very large. I could easily sit in this one! Credit: L. White

So, how can we figure out how many northern hairy-nosed wombats are left and whether the population is growing or shrinking? By using DNA!

Faecal pellets, shed skin, saliva, feathers, and hair are all easily gathered sources of DNA for difficult to observe animals. For the northern hairy-nosed wombat, hair is collected by stringing double-sided sticky tape across their burrow entrances. As the wombats enter or exit their burrows overnight they get a small wax and hair is stuck to the tape.

Sample

Sticky tape strung across a burrow entrance (left) and wombat hair stuck to the tape (right). Credit: L. White

DNA extracted from this hair is then analysed using several genetic markers that enable us to distinguish one wombat from another, in much the same way DNA is analysed in human forensic cases.

Wombat barcode

Wombat Chromatogram Credit: L. White

This chromatogram image shows the result of using the genetic markers on one wombat. The pattern of peaks is unique to that specific wombat, much like a barcode is unique to a single item at the store. By collecting hair over several nights, population size estimates can then be calculated by seeing how many unique wombat barcodes we find and estimating what proportion of the population we are likely to have sampled. Such hair censuses are conducted every 2-3 years for the northern hairy-nosed wombats and have shown a steady increase in population size since 2000.

As an Honours project, my supervisor, Associate Professor Jeremy Austin, and I made the DNA analysis quicker and easier by re-designing the genetic markers used. To test whether these markers would serve their purpose, we used them to re-analyse the hair samples from the 2010 census. Our method estimated a population size of 173 wombats! This closely matched the population estimate found using the previous genetic marker set, demonstrating that our method was not only quicker and simpler but also as effective as the previous technique.

As a result of my research, I was lucky enough to be invited by the Queensland Parks and Wildlife Service to partake in the hair census that took place in September 2013. I flew up to Queensland and spent two weeks in the field collecting wombat hair samples at the dismally dry, but nonetheless beautiful, Epping Forest National Park. I now know first hand how difficult the wombats are to spot. The whole two weeks I was there, I only saw two!

Wombat Lauren

One of the two wombats I actually saw during my time at Epping Forest NP. Credit L. White

In total, we collected 1,260 individual hairs! Every single hair was carefully placed in its own (very) small tube, a task that involved tweezers and no small amount of patience. Once collected, I transported the samples back to the ACAD lab and am now getting psyched up to begin analysing them. Hopefully, this next population estimate will continue to show that the northern hairy-nosed wombat population is growing, giving the green-light for more reintroductions and recovery action. Using DNA analyses as part of the conservation effort, we hope to make sure wombats are here to stay.

To check out the great conservations efforts of Queensland, visit the Department of Environment and Heritage Protection website here.

For more cool pictures of the northern hairy-nosed wombat visit the EHP website here.

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