Post by Lindsey Zarecky, VP of Conservation & Research
During the month of October, four GSC staff members journeyed to the Caribbean to participate in a laborious data collection study to help protect the endangered Mona iguana. Mona Island, affectionately referred to as the Galapagos of the Caribbean, is home to many rare and endemic species. This 34-square-mile island is located between Puerto Rico and the Dominican Republic on the Mona Passage.
One of the endangered species on the island is the Mona Rhino iguana. This large-bodied, slow-growing, ancient-looking lizard thrives in the hot, humid environment found on the island. Today Mona does not have any permanent residents as it is a difficult island with no freshwater access, tough terrain, and unfriendly vegetation. But, humans have lived there in the past, utilizing the many caves on the island. And, explorers visited in the past and brought with them other vertebrate species, which are now a major threat to the iguanas and other native wildlife. Feral pigs, cats, goats, and rats threaten the future for the iguanas as they predate on the eggs, hatchlings and juvenile iguanas, compete for resources, and destroy nesting habitat.
Over 20 years ago a population survey was completed and estimated there to be around 5,000 iguanas. This is a very low count compared to similar iguanas on other islands. Even more concerning is the lack of recruitment by the species, with only 5-10% of the population being juveniles. In order to enact change and remove invasive species, we first need to understand the population.
Therefore, in October 2019 GSC staff joined our Puerto Rican partners on Mona Island. After a 6-hour boat ride, our team arrived on Mona Island – a towering rock of limestone, greenery, soil and sand. Eight teams of two people set out to lay 200-meter-long transects around the island in a randomized pattern. Those transects were then surveyed over the next three weeks. Every iguana seen while walking the transect was counted and included in the study. Each transect was surveyed multiple times and data is currently being compiled. The same survey will be replicated in October 2020.
Staff had the opportunity to experience the beauty and challenges found on Mona Island. The terrain is jagged and unforgiving. The temperature is hot, the bugs voracious, and the cacti are prevalent. But, there were also moments of wonder and beauty as we stepped on rock very few others have or will ever get to explore. The endemic plants and animals provided rare photobook memories. And the people we worked with were just wonderful and by far a highlight of our experience.
For many years, the GSC has been informing guests about conservation of species. But providing a hands-on, field experience in such a physically and mentally demanding island left lasting impressions on the staff who participated. We can only hope this work and the work we will do next year provide the data needed to support our goal of protecting Mona iguanas through removal of vertebrate invasive species. Stay tuned – we will continue to bring you more information about the great conservation work and scientific research taking at the GSC.