Tourist Trap! Saving the Rock Iguanas

By: James Heffernan

When you picture a vacation in the Bahamas, is one of the possible activities you might do there feeding an exotic lizard a snack? For most people, the answer is probably no, but not only is the number of people who do this surprisingly high, but it’s having a significant impact on a species of iguana in the Bahamas. Scientists have learned that many different factors can lead to species splitting off into multiple species or subspecies. This is called speciation. One such factor lead to speciation is human interaction, and a study by researcher Susannah French and colleagues have found this is exactly what is happening to the endangered northern Bahamian rock iguana. The researchers wanted to know how tourism was affecting different populations of iguanas who had varying degrees of human interaction, ranging from seeing hundreds of tourists in a single day to having virtually no human interaction at all.

The researchers first found distinct groups of iguanas to be used in their study, which one of three levels of tourist interaction: high (average of over a hundred visitors per day), moderate (around twenty visitors per day) and none (no visitors at all). They confirmed with genetic testing that there was very little chance that individual iguanas would have migrated between groups, meaning each group would have distinctly different amounts of human exposure. Individual iguanas were captured randomly from each group, and tests like blood samples and determining egg clutch size were done by the researchers. The researchers then performed mathematical tests on their results to see which findings would be useful for determining how tourism affected the rock iguana.

Many of the tests the researchers did confirm that there were significant differences in many aspects of the rock iguanas in each population. These differences suggests that there could conceivably be multiple species of iguanas that are arising from an already endangered population. Not only that, but there is a good chance this change is directly caused by human interaction via tourism. The researchers found that there were differences that were noticeable between each group of iguanas, while there were some that were only notable distinct comparing the high human interaction group to the no human interaction group. One notable result was that iguanas in high-tourism populations actually had a better immune response compared to iguanas in the other populations.

Human interaction is directly affecting populations of an endangered animal in a highly frequented tourism destination, down to differences in their level of body chemicals. This is very likely to lead to the northern Bahamian rock iguana splitting off into multiple species, putting an already at risk species into more danger. While there have been some beneficial effects observed from this, like a higher immune response, the researchers note that these changes in the iguanas are only just starting. There is no way to know how human interaction will affect them until it’s possibly too late.

All of this is not to say, never interact with an animal again. Of course, even if you wanted to, this is quite literally impossible. But, it’s important to know that what may seem like a fun and harmless activity, like feeding an exotic animal a snack while on vacation, may actually have a significant lasting impact on that animal’s species for years to come. Not only that, but the affect may not be discovered until it is too late. For an endangered species like the northern Bahamian rock iguana, appreciating them from afar to help preserve them for future generations.

French, S. S., Webb, A. C., Wilcoxen, T. E., Iverson, J. B., DeNardo, D. F., Lewis, E. L., Knapp, C. R. (2022). Complex tourism and season interactions contribute to disparate physiologies in an endangered rock iguana. Conservation Physiology. 10, coac001.