Since the early 2000’s, I have studied the food habits of Northern Bahamian Rock Iguanas in the Exumas and have observed slow but steady changes in iguana scat (feces) on islands with the heaviest food supplementation from tourists. A healthy iguana scat looks like a cigar, consisting of tightly rolled leaves and fruit that often remain intact. In areas of food supplementation, where the iguanas are predominantly fed grapes and melons directly on the sand – foods containing higher liquid concentrations than native plants, many of the scat dry to cement-like cylinders that consist almost exclusively of sand and grape remnants. Collaborators and I have documented medical issues likely associated with this dietary shift and are currently exploring the physiological implications.
I’ve also studied behavioral differences between visited islands and non-visited islands. Iguanas on visited islands are less wary of human presence than those on non-visited islands, making them more susceptible to poaching and to potential mortality from non-native predators if cats or dogs were ever introduced to the island. Other studies have also noted demographic changes potentially linked to tourist visitation. While documenting these shifts is relatively straight forward, understanding the nuances of these changes and potential long-term impacts is less so. And understanding the character and implications of these changes is essential to developing successful management strategies for the survival of this species.
Surprisingly, there has been no comprehensive reporting of the natural diet of Northern Bahamian Rock Iguanas to date, and characterizing their native diet is a critical step in this process. I am currently analyzing scat samples collected over the past six years from the non-feeding areas of 15 different iguana-inhabited islands. My preliminary results suggest that the native diet of Northern Bahamian Rock Iguanas in the Exumas consists primarily of four species of plant – Seven Year Apple, Buttonwood, Sandfly Bush and Wild Dilly. They are, however, opportunistic foragers, grazing on over 40 plant species and consuming animal protein as available through scavenging and even occasional hunting.
Results from this research have contributed to educational materials, have been presented at scientific meetings and have been published in scientific journals (see list below). For more information about these iguanas, please see my Exuma Iguana Awareness page.
Hines, KN. 2011. Effects of ecotourism on endangered Northern Bahamian Rock Iguanas (Cyclura cychlura). Herpetological Conservation and Biology 6(2):250-259. [Hines_2011_herpconbio]
Hines, KN, JB Iverson and JM Valiulis. 2002. Cyclura cychlura inornata (Allen Cays Rock Iguana): Bird predation. Herpetological Review 33(4):306.
Hines, KN, JB Iverson and JM Valiulis. 2002. Leiocephalus carinatus virescens (Exuma Curlytail Lizard): Interspecific Aggression. Herpetological Review 33(4):308.
Hines, KN, CR Knapp, TT Zachariah, JB Iverson and GR Smith. 2010. Cyclura cychlura inornata (Allen Cays Rock Iguana). Paraphimosis and prolapsed cloaca. Herpetological Review 41(1):77-78.
Iverson, JB, KN Hines and JM Valiulis. 2004. The nesting ecology of the Allen Cays Rock Iguana, (Cyclura cychlura inornata) in The Bahamas. Herpetological Monographs 18:1-36.
Iverson, JB, CR Knapp, KN Hines, SA Pasachnik, and L Pieper. 2011. Cyclura cychlura inornata (Allen Cays Rock Iguana) Mortality. Herpetological Review 42(2):274. [Iverson et al 2011_herp rev]
Knapp, CR, KN Hines, TT Zachariah, C Perez-Heydrich, JB Iverson, SD Buckner, SC Halach, CR Lattin, and LM Romero. 2103. Physiological effects of tourism and associated food provisioning in an endangered insular iguana. Conservation Physiology 1:1-12. [Knapp et al. 2013_ConsPhysiol]
Smith, GR, KN Hines, S Pasachnik, L Pieper, E Phelps, and JB Iverson. 2009. Cyclura cychlura inornata (Allen Cays Rock Iguana). Cause of mortality. Herpetological Review 40(3):341-343.
Valiulis, JM, KN Hines and JB Iverson. 2003. Adventures of the Iguana Patrol, p. 39-48. In RW Henderson and R Powell (eds.), Islands and the Sea: Essays on Herpetological Exploration in the West Indies. Society for the Study of Amphibians and Reptiles, Ithaca (New York). Contributions to Herpetology, volume 20.