Tipping the Scales for Rock Iguanas
Temperatures rage in the Caribbean during the summer, easily reaching 110 degree by late morning. We wake up with the sun to start our research, monitoring iguana nests and radio-tracking hatchling iguanas, before the heat becomes overpowering. Then, just as the iguanas do, we hide from the midday heat. We finish out the day with an afternoon shift, often finding our way out with headlamps.
Rock iguanas are among the most endangered reptiles in the Caribbean, yet they are a very important part of the ecosystems in which they live. Unfortunately they are disappearing and desperately need our help. Given their large size, these iguanas are often targeted for food. But invasive, nonnative species and habitat destruction also threaten them.
Just two months ago, an international crisis began. I traveled to a remote part of the Dominican Republic (DR) to run a series of transects. The goal was to record evidence of iguanas and illegal charcoal production, in order to understand how the charcoal trade is affecting iguanas. We were delighted to find iguanas in good numbers in one area of this subpopulation. We returned to our home base in the southwest DR to find that this exact area was set to be clear-cut. Devastated, we contacted the International Union for the Conservation of Nature (IUCN) and worked together to stop this destruction.
Hispaniola (DR and Haiti) is the only place in the world where two species of rock iguanas co-exist. This creates an interesting situation, where we need to understand how these two species deal with one another. Specifically, we are looking at how they share nesting areas and where their offspring go.
I just completed three months of fieldwork in southwest DR. The season began with nest encounters. We want to know if there are differences in the nest characteristics between species, so we had to find the nests. At first, this was very challenging, but we quickly learned to recognize the signs of a nest.
The next challenge was how to get into the nests without endangering the eggs. It turns out, it is not that difficult as long as you have the proper training, which we got from Dr. Glenn Gerber, San Diego Zoo Global scientist.
So, how do we do it? To be honest, it is a very slow and dirty process. Some nests took us up to two days to find! The nests can be 6 feet deep and over 16 feet long, which means we spend a lot of time lying in the dirt. We have come to call this dirt bathing. Just when you feel you will never find them, the tip of your finger touches an egg and makes it all worth it.
Jump ahead to the next half of our field season, and we are monitoring the nests to see when the hatchlings emerge. We put corrals around where we think the babies will come out so we can catch them. Then, a few of them get radio collars put on so that we can follow them on their adventure away from the nest. This too gets complicated, as they can easily make their way through thick cactus groves and up steep limestone cliffs. But, in time, we also find our way through and we get to see just where they ended up. Sometimes they are basking on top of a cactus, sometimes hiding in a hole in the ground. Nothing beats that moment when you finally find that little iguana!
Stesha Pasachnik, Ph.D.
Postdoctoral Research Associate