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The Natural History and Captive Care of the Rhinoceros Iguana

Male Rhino IguanaRhinoceros Iguanas (Cyclura cornuta cornuta) rank among the most “personable” of the lizards I’ve worked with.  However, due to their size, unique needs and powerful jaws (please see below), the decision to keep these magnificent animals must not be made lightly.


The “bulldog-like” body is stoutly-built and colored uniform gray, brown, olive-brown or nearly-black.  Rhinoceros Iguanas reach 4 feet in length, but appear larger due to their bulk.

The massive head of the male is topped by 3 horn-like tubercles and a thick adipose (fat) pad.  The head and horns of females are smaller. Both sexes have large throat pouches and crests of pointed scales along the spine and tail. 


The Rhinoceros Iguana is limited to Hispaniola (Haiti and the Dominican Republic) and several small nearby islands.  Navassa and Mona Islands are home to 2 additional subspecies, but the Navassa Island animal may be extinct.

The genus contains 7 other species.  All are island endemics (Cuba, Jamaica, Caymans, Bahamas) and critically endangered.


Dry, rocky cactus and thorn bush scrub forms the primary habitat.  In earlier times, populations were concentrated along the coastline, but development has now pushed most into the island’s interior.

Rhinoceros Iguanas are diurnal and shelter in long, self-dug burrows.

Status and Conservation

Populations have plummeted due to development, logging, over-grazing, limestone mining and predation by introduced rats, cats, pigs, mongooses and dogs.  Over half of their habitat in the Dominican Republic is gone, and the remainder is severely degraded; the situation appears far worse in Haiti. 

The Dominican Republic has protected Rhinoceros Iguanas for over 20 years, but hunting for the table continues in Haiti.  They are listed on CITES Appendix I and classified as “Vulnerable” by the IUCN.

A number of zoos and hobbyists are breeding this animal, and predator-removal and reintroduction programs are in place in the Dominican Republic.

C. cornuta stejnegeri, the subspecies on Mona Island, is protected under the US Endangered Species Act.  A disease that causes blindness often affects the Mona Island’s iguanas; research is in progress.

Rhinoceros Iguanas in Captivity

Green Rhino Iguana


Male Rhinoceros Iguanas fight for breeding opportunities.   Mating occurs in May and June.  In August, females excavate nesting burrows that may reach 5 or more feet in length.  Their 5-30 eggs are deposited at the end of the burrow and are guarded for at least part of the 4-5 month incubation period.  Sexual maturity is reached in 5-9 years.


Adults are largely herbivorous, consuming plants, berries, seeds and the pads, flowers and fruits of cacti.  At certain times of the year, land crabs, snails and beetle grubs comprise much of the diet; dead birds and fish are also taken.

The young eat proportionately more animal prey than do adults.  Rhinoceros Iguanas vigorously defend temporary food sources, such as fruiting trees.

Captives show evidence of well-developed learning abilities.  One under my care for many years approached immediately at feeding time but learned that 2 people entering the exhibit, even if bearing food, meant trouble (i.e. restraint for medical treatment).  If 2 people entered its exhibit, the lizard would immediately retreat.

Long term captives may become quite calm, but the danger from their immensely powerful jaws is ever-present.  My thumb was severely injured by a “tame” specimen; it was only by chance that I escaped permanent nerve damage.

Further Reading

Breeding the Rhinoceros Iguana at the Australia Zoo.

Rhinoceros Iguana Conservation.

Video of wild Rhino Iguana.



Green Rhino Iguana image referenced from wikipedia and originally posted by Elliot Brown

About Frank Indiviglio

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Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.
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