Rhino Iguana

The rhinoceros iguana, also commonly called the rhino iguana, is a species of large, heavy lizards native to the tropical islands in the Caribbean. Part of the iguana’s name is derived from the bony protrusion on its snout that is similar to a rhino’s horn. Apart from the nominate subspecies, the Hispaniolan rhinoceros iguana, two other subspecies have been identified, including the extinct Navassa Island iguana and the extant Mona ground iguana.

Physical Description and Appearance

Size: These large-sized reptiles vary in length, ranging from 60-136 cm (24-54 in).

Weight: Adult rhino iguanas, being large-bodied lizards, are quite heavy and weigh between 4.56 and 9 kgs (10.1 and 19.8 lb).

Color: Their skin color ranges from a uniform steel gray to dull brown or dark green.

Body: They have a large, sturdy body with a crest of horned scales, extending from the back of their neck to the tail. They are characterized by strong legs, bony, horn-like outgrowths on their snouts, and a tail that is flattened vertically.

Sexual dimorphism: Males have a larger body than females, with a more prominent horn-like protrusion and dorsal crest. They also possess pheromone-secreting femoral pores on the inside part of their thighs.

Distribution

The native range of rhino iguanas includes the Dominican Republic, Haiti, and Hispaniola. Stable populations of these lizards are found only on the Beata Island and inside the Jaragua National Park in the Dominican Republic.

What Kind of Habitats do Rhino Iguanas live in

These iguanas primarily inhabit the scrub woodlands, deserts, dry forests, and rocky outcrops with little vegetation. They are also found near coastlines, but human expansion has caused them to move further back inland. Mostly shrubs, cacti, and small trees like mesquite encircle their burrows.

Lifespan

Rhino iguanas may have a life expectancy of around 10 years in the wild, and they are reported to have lived for more than 20 years in captivity.

Diet

The rhinoceros iguanas primarily feed on leaves, fruits, flowers, and berries from various plant species. They are also opportunistic carnivores, as some specimens have been observed hunting small birds, insects, snakes, and lizards.

Behavioral Characteristics

• They are a diurnal species, and they spend most of the time basking in the sun to maintain their body temperature.
• They are mostly terrestrial reptiles and are rarely found on trees.
• These reptiles usually flee when attacked or threatened. They will, however, aggressively bite and repeatedly strike with their tail if cornered.
• Males are territorial and may aggressively defend their territory during mating season.

Adaptations

• Their bony horn-like protrusions, along with the parietal bulges and spines on their back, work as a protective armor against rocks. They also use these anatomical adaptations to escape from the grasp of enemies or predators.
• They have thick, powerful tails, which they use for whipping a predator that attacks them.
• Their skin color works as camouflage, allowing them to blend in with their environment.

Mating and Reproduction

The mating season usually starts in late May and may extend through June. Male rhino iguanas use rapid movements of their head and body to intimidate other males as well as to attract females. Once a female iguana responds to the male’s mating display, the male mounts the female. A male may have several mating partners.

Females dig deep burrows, which may measure 1.5 meters long. They lay approximately 17-18 eggs within 40 days after mating. They guard their nesting sites and incubate their eggs for around 85 days. The males become sexually mature at 4-5 years of age, while the females reach sexual maturity when they are 2-3 years old.

Conservation Status

Even though they are among the most common species of rock iguanas kept in captivity, only 10,000-16,000 rhino iguanas exist in the wild today. A breeding program at the National Zoological Park in the Dominican Republic continued till 1994, producing around 100 babies annually. These babies were later reintroduced in protected habitats to lessen the chances of predation. This program, however, has been discontinued since 1995, because of an administrative change. Rhino iguanas have been acknowledged as an ‘Endangered’ species by the IUCN.

Interesting Facts

• Rhino iguana eggs are probably the largest eggs produced by any lizard species in the world.
• Although the rhinoceros iguanas are not as big as the green iguanas, their weight is twice that of their green cousins.
• Their populations in Haiti have become more endangered, not just due to deforestation but also because of hunting by the locals for iguana meat.