A critical component of this study is being able to keep track of who is who, every single year. There are a lot of tried and true methods for doing so, including the low-tech of removing the last joint of different combinations of toes. There’s the mid-tech: injecting multi-colored liquid plastic that congeals just under the skin to give a unique marker. Finally, the high-tech (and my favorite): PIT tags. PIT stands for “Passive Integrated Transponder” which means little tiny circuit that, when activated with an electrical current, replies with a unique identification code.
While toe clipping is a very common means of keeping track of individuals, it suffers from problems because lizards lose toes all the time in fights. To our knowledge though there are not yet PIT tag parlours on any of these islands (though I think the lizards think they’re really cool) so we can be very sure that we’re getting exactly the individuals we want.
The process of implanting a PIT tag is remarkably straight forward. Here’s a video:
As you can see, the PIT tag is tiny – it doesn’t seem to affect the lizard’s movement or behavior at all. Next year, we’ll be able to know exactly who is who!