Colin Donihue

There isn’t a whole lot of fancy equipment necessary for my research (more’s the pity!). Last year I posted a description of the bite force meter I’ve been using. This year it’s back in action. You can see it here and click the link to read a bit more about how it works.The components have been “exploded” a bit so you can see how they all fit together. The bite force meter has been a tremendous asset and has revealed some fascinating differences between populations of Podarcis between islands and even within islands.

The question though remains, what does it mean that the bite forces are different? Does that difference result in an advantage for different circumstances? There are two broad cases where bite force makes a big difference for these lizards, the first is in what they can eat, and the second is for how well they can compete with other lizards.

So what are these lizards eating? Well, I’ve watched them for hours but it’s a little hard to notice what all they’re chowing down on. Others spend time picking through fecal pellets but avoiding poking Podarcis poo was a personal goal of mine for this summer. That leaves stomach flushing. Here are the tools for that:

At the most basic level, stomach flushing works entirely as you’d guess. You can see a video my friend made of the procedure in crocodilians. Those circular rings sit in the mouth of my little lizards, keeping their jaws open.  I then fill the syringe with water, insert it into the mouth of my little lizards and gently start the flow of water. With a little bit of coaxing, all of a sudden all sorts of insects start popping out into the awaiting strainer. I’ve found beetles, flies, bugs of all sorts, and caterpillars almost as long as the lizards themselves! So far we’re getting a really terrific sense of just what these lizards are selecting to eat and there’s a lot of variety between different sites. The next step is to start sorting through all of the data for figure out what it all means and how it relates to bite force!