The reptile keepers at Taronga Zoo’s Reptile World watched five little rhinoceros iguanas hatch from their eggs in late April. So far, all of them are thriving. The keepers have successfully hatched and reared over 100 of these iguanas in the past, so they’re well-versed in the breeding and raising of this species.
When the eggs were laid by the adult Rhinoceros Iguana in January, keepers took the eggs to be incubated separately. In the wild, many lizards, such as iguanas, goannas and dragons deposit their eggs in the soil, burying them. They will meticulously search out the most ideal nesting sites which will give their eggs the best prospect for hatching. In zoos, these lizards still bury their eggs but to reduce the variables, particularly temperature fluctuations, which might adversely affect hatching, keepers remove the eggs to an incubator, which is a controlled environment.
Two of the most important factors in incubating reptile eggs are a constant warm temperature, about 30°C, and a suitable incubating medium. The eggs are gently nestled into the mixture of vermiculite and water so that they are just covered, taking great care not to turn them. In the case of our Rhinoceros Iguana’s eggs, if they are fertile, the warmth and humidity will ensure that young will hatch unassisted in about 110 days.
The iguana hatchlings are kept on the same diet as their adult parents of what we call “iguana mix”. This is a combination of fruits and vegetables chopped and mixed together, and sprinkled a mix of multivitamin and calcium powder. This ensures the babies and adults receive the best diet. In addition, they are fed foliage like mulberry leaves, hibiscus flowers and other edible vegetation.
When these iguana hatchlings have grown, some of them will be placed on display here at Taronga Zoo. Others will be transferred to other zoos within Australasia, many of which have received some of our Rhinoceros Iguanas in the past.
Rhinoceros Iguanas are native to the island of Hispaniola in the West Indies and grow to over a metre in length. They are classified as Threatened on the island, which is shared by the Dominican Republic and Haiti. Besides human impacts on their environment; they are also hunted by feral animals such as cats and mongooses.