Rhinoceros Iguana (Cyclura cornuta)
Order: Squamata, Family: Iguanidae
The rhinoceros iguana is found only on the island of Hispaniola in the Caribbean Sea. A closely related species or subspecies (scientific opinions vary) was found on Navassa Island, but is now believed extinct. There is a living subspecies on Mona Island, near Puerto Rico.
I. GEOGRAPHIC RANGE
II. PHYSICAL CHARACTERISTICS
- The rhinoceros iguana is found only on the island of Hispaniola in the Caribbean Sea. A closely related species or subspecies (scientific opinions vary) was found on Navassa Island, but is now believed extinct. There is a living subspecies on Mona Island, near Puerto Rico.
III. FOOD HABITS
- Mass: 28.6 to 48.4 kg.
- The skin of the rhinoceros iguana has rough epidermal scales and is grayish brown or olive in color.
- The species is definitively identified by the large size of certain scales on the head; few other iguana species are as large or have these "horns" (actually enlarged scales) on their heads. These horns are the source for the name for of the species. Males are larger than females and have relatively larger horns as well.
- Rhinoceros iguanas have a variable diet both seasonally and ontogenetically. Rhinoceros iguanas are mainly herbivores, eating a wide variety of leaves, fruits, flowers and seeds. They occasionally eat animal food, mainly insects, land crabs, or carrion. Young iguanas in particular may take insects and other small animals.
- Rhinoceros iguanas that locate a food source (for example, a fruiting bush) will actively defend it from others of their species.
- The beginning of the mating season is late May.
- The rhinoceros iguana is oviparous, thus eggs are laid about 40 days after mating, usually in early August.
- Females dig burrows up to a meter and a half long in which to incubate the eggs and must keep them at a minimum of 30 degrees Celsius. Clutch size is extremely variable and may range from 5 to 20 eggs. Resource competition and/or abundance of predators is thought to account for variations in egg-laying behavior.
- The rhinoceros iguana appears to be extremely territorial and males especially will attempt to dominate and intimidate other males with head movements and body gyrations. They use similar motions to attract females, and may also use these head bobs and nods to scare away predators.
- There is no male parental care this species. Once females have laid their eggs, they sometimes guard the nest for a few weeks to prevent egg predation.
- Like all iguanas, rhinoceros iguanas adjust their activity patterns to utilize solar radiation so as to regulate their body temperature.
- Most of the documented behavior unique to the rhinoceros iguana revolves around mating behavior. The aggressive displays that accompany mate guarding and territoriality have been discussed above.
VII. ECONOMIC IMPORTANCE FOR HUMANS
- The natural habitat of the rhinoceros iguana is typically described as dry forest, scrub or desert. This biome receives very little rain annually, and the plants and animals that occupy it reflect the sun-drenched, arid environment. Mostly small trees and shrubs, cacti, and mesquite may surround the burrows that the rhinoceros iguana inhabits.
- This species is primarily found near coastlines; however, human expansion has forced many populations to retreat further inland.
- This species requires warm temperatures and lots of solar radiation. The rhinoceros iguana is typically found in regions where the annual mean temperature is at least 27 degrees Celsius.
Rhinoceros iguanas are sometimes kept as pets, and in the past have been used as food. Currently they are not of great economic importance.
This species will bite or scratch and strike with its tail if provoked or attacked, but is otherwise harmless and in no way detrimental to humans.
IX. OTHER COMMENTS
- The rhinoceros iguana is threatened by human encroachment on and destruction of its natural habitat. The demand for old growth trees by the logging industry, limestone mining, pollution, predation and wild fires have depleted the habitat and often forced this and many other species to migrate and/or go extinct.
- Haiti, a country mired in poverty, in particular has experienced a dramatic reduction in population due to poachers killing for food.
- This species is listed as Vulnerable by the International Union for the Conservation of Nature, and is listed in Appendix I of CITES. This means that international trade in this species is generally forbidden with out strict permits from both exporting and importing countries.
- There is legal trade in captive-bred rhinoceros iguanas. Potential purchasers should always insist on full documentation to ensure that they are not getting illegally collected wild animals. Illegal collection endangers the species and is bad for the pet trade, as wild animals often carry parasites and diseases that have been eliminated from captive-bred populations.