Imagine visiting the subtropical paradise of The Bahamas. Instead of holding a drink, you’re grasping a net. Instead of sand between your toes, you’re navigating sharp limestone in boots. Instead of admiring beautiful sunsets, you’re searching for beautiful iguanas. You can find drinks, sand, and sunsets in many destinations, but if you’re part of Shedd Aquarium’s iguana research team, you’re looking for an animal found only on the Bahamian island of Andros. The memories of those sunsets may fade, but some, including me, the memory of stumbling upon a 10-pound iguana, or spotting a four-ounce baby iguana hiding on a mangrove root, lasts a lifetime.
I’m Dr. Chuck Knapp, Shedd’s Vice President of Conservation and Research. Since 1999, Shedd Aquarium and our partners from the Bahamas National Trust (BNT) have been studying the endangered Andros iguana (Cyclura cychlura cychlura), which in my biased opinion is the most beautiful of all iguana species. The Andros iguana is also unique because it is the only iguana in the world that lays eggs in active termite mounds, where they remain warm and dry during summer floods. Fortunately, termites don’t seem to mind the disturbance from iguanas digging holes in their mounds.
A challenging landscape
Andros iguanas are uniquely suited to their island ecosystem but vulnerable to human pressures, including hunting, habitat destruction, and predation by invasive species. In 2009, the Bahamian government expanded the West Side National Park to include critical iguana habitat and populations, a decision informed by Shedd’s detailed life-history studies and by population assessments accomplished with help from our citizen scientists. For nearly two decades, these dedicated participants have traveled from North America and Europe to slog through mud and crawl through brush in support of research that directly benefits iguana conservation. Our work is particularly important because long-term ecological studies are costly and rare, especially in remote, understudied places like Andros.
Recently, we returned to Andros onboard Shedd’s research vessel, the Coral Reef II, with our citizen science team, BNT representatives, and Giuliano Colosimo, a Mississippi State University graduate student with Dr. Mark Welch. Among our goals: revisiting iguana populations that we’ve studied for over a decade to monitor their health and collect data on long-term growth and survival. We revisited two sites first surveyed in 1999 and 2001. Since then, we have investigated how individuals and populations fluctuate through time using mark-recapture techniques. It isn’t easy. Iguanas occur in extremely low numbers on Andros, and traversing the tangle of vines and poisonwood without falling into concealed holes is challenging.
The hard work is worth it when you experience the adrenaline rush of finding an elusive iguana in this harsh landscape. To the human eye, iguanas blend seamlessly with the environment and yet, once spotted, they are so conspicuously beautiful. Once spotted, our trained citizen scientists work in concert to harmlessly secure the iguana so I can take measurements, draw blood for genetic analyses, and insert an identification tag like the microchips used for cats and dogs.
At the smaller of these two locations, 11 of our 12 iguanas sampled this year were recaptures from past years–three of them originally tagged in 2002! At our other location from a larger, main island, 5 of 9 iguanas were recaptures. Recapture data provides us with growth rates and survivorship information and allows us to calculate population estimates. Our ongoing presence in these remote areas also allows us to identify and quickly respond to ever-persistent threats such as domestic cats, feral hogs, or poaching.Dr. Chuck Knapp holds Norte, a frequent recapture and favorite individual from his many years of field research on Andros Island in the Bahamas (Shedd Aquarium).
These trips have a clear conservation impact, but it’s harder to explain the unique affinity you develop for iguanas over time. I have gotten to know some of the individual animals, including a favorite female that we recaptured this year. We originally worked with her in 2001, and I radio-tracked her for many months in 2003 and 2004 while studying her nesting behavior. She is at least 20 years old, probably closer to 30. For me, the long-term interaction with these amazing creatures underscores the sense of urgency for our work and fortifies my determination to help this species survive. If you want to know how it feels to directly help save a species, I invite you to learn more about our next trip by contacting IguanaResearch@sheddaquarium.org. Stay tuned for my next post on swimming iguanas and population genetics.