Monitor Lizard and Western Australia: Deep, Spiral Burrows

Monitor lizards in western Australia are no slouches at burrow creation. They'll dig deep, and go far, to create a place to leave their eggs . Turns out that the way they're doing it is extra-special.

That is, researchers at the University of Newcastle, Australia, say that the yellow-spotted monitor, or Varanus panoptes, is the first reptile to make helical burrows--nesting spots that burrow deep into the earth, using spiral construction. In the monitor's case, they are often nine feet deep. 

Burrows of this type are known as a devil's corkscrew. Fossil versions were found in the late 1800s, perplexing scientists. Later it was discovered that they had been dug by an extinct beaver, the Palaeocastor.

In the current day, why would these swagger-y looking lizards dig so deep? It might be to provide moisture to eggs during the long dry season, thinks lead researcher Sean Doody, according to the journal article.

The research included excavating 52 burrows clustered in the savannah woodlands of Western Australia's Kimberley region--then recording measurements, including temperature and humidity readings.

Regarding the spirals, Doody theorizes that their shape might deter predators, or promote drainage from flooding early in the nesting season. Alternatively, it might help lizards excavate, by keeping soil from falling back in as they dig, according to the journal article.

In any case, Doody says this monitor lizard has the most stable nesting environment of any known reptile.