Sunday, 11 May 2014

How to catch a giant varanid lizard


Recently at the SEB conference in Spain I convinced a muscle expert, Taylor Dick from Simon Fraser University in Canada, to come out to Australia to study muscle variation in Australian varanids. The purpose of this study was based upon a previous paper I had written “Lizard Tricks” of which I wrote a blog about here. But incase you missed it, basically I had found that differences in the Kinematics of the lizards hindlimb were not based upon changes in lizard size (as I had expected) but rather were related to changes in the lizards habitat. The Arboreal lizards (both big and small) had a crouched, sprawling posture, as if they were in a perpetual pushup, the terrestrial lizards (again both big and small) had a more upright posture. The reason for this difference was probably since arboreal lizards wanted to be close to the surface they were climbing on to avoid toppling over (and so had the crouched posture), while the terrestrial lizards wanted to improve stride length, and so had longer more upright limbs.

But the problem with this is that these changes in posture are going to cause big changes in limb bone and muscle stresses, especially in the bigger guys. And so that’s where Taylor came in. She was to come over and study the differences in the forces produced while running and look for any differences in muscle architecture between climbing and terrestrial lizards, and in doing so hopefully solve the problems I had created.

But I wasn’t going to make it easy for her. No sooner had she got off her Trans Canadian flight (or whatever passes for airlines in Canada) than we were off to the bush to catch some giant varanids. And so the rest of this blog serves as a first persons perspective to the type of skills required to catch these big lizards. The first day turned out rainy and miserable, and the only reptiles we ended up seeing were a couple of turtles which were trying to cross the road. And soon Taylor learnt a valuable lesson in using the dunny block in the outback when she ran out of the toilet screaming cause a (in my opinion) particularly friendly looking green tree frog happened to be occupying the toilet seat she was hoping to utilise.

But soon the sun did eventually shine, and by the third day we spotted our first lizard. It was a medium sized Varanus varius. Being members of the most uncooperative group of reptiles typically they will choose the tallest and most unclimbable (well for humans) tree as an avenue of escape, but this lizard made the poor decision of escaping up a perfectly good climbing pine tree. The secret to catching a lizard up a tree is that it is generally better to be stupider than the lizard. And so I found myself most of the way up a tiny swaying pine tree chasing a lizard which, unsurprisingly had climbed to the very meagrely supported top. However I was successful in getting the noose over its head and coercing it back down. We had caught our first lizard.

The second lizard proved to be smarter than the first. It chose a very thin, but extremely tall gum tree as its method of escape. My first attempt to get it down involved taping three lengths of beach fishing rods, with a long noose, together. I had tried this technique before, and previously it had failed spectacularly, but I was sure the theory was sound. Sometime later I had added another failed attempt to my list, yet I still feel deep inside, one day, my patented super long lizard noose technique might just work. In the end, it was the less eloquent but ultimately more successful technique of shaking the bejesus out of the tree enticed the lizard down to a lower and more manageable height in the tree.


The next two lizards we caught were two very large Varius which were in comparison much easier to catch. We found them wondering around the local garbage tip, which might explain their smell, and their indifference to my presence. They barely climbed to head height up the nearest tree and thus were relatively easier to coerce down. And so we returned to Brisbane, maybe not somewhat wiser but certainly four big lizards the richer. The next part of our plan was to run them over the force platform.