Cayman’s Blue Iguanas are breeding! Everything you want to know… | Loop Cayman Islands

The content originally appeared on: Cayman Compass

If you have visited the Blue Iguana Conservation (BIC) facility recently, you may have noticed that the iguanas are paired up for breeding season. This basically means that some matchmaking has been going on behind the scenes.


Through years of conducting population census surveys, there is strong evidence to show that there is a lack of natural recruitment (this means live births in the wild). As a result, captive breeding is required.

In order to increase genetic diversity in the blue iguana (Cyclura lewisi) population, Tandora Grant, Conservation Program Specialist in Population Sustainability with the Wildlife Alliance at the San Diego Zoo, one of BIC’s long term partner institutions, manages the Grand Cayman blue iguana studbook from which breeding iguanas are selected.

The Blue Iguana studbook informs which individuals are to be paired each year to increase genetic diversity within the population and also according to size to avoid unnecessary aggression and harm to the iguanas. Ms. Grant evaluates genetic and demographic statistics to determine captive breeding pairs and wild release candidates. She incorporates molecular data in order to further define the fitness of reintroduced populations and guide management actions.

Blue iguana pairs are placed in robust facility structures at the breeding facility in North Side to live together for several months.

Due to climatic changes, breeding season begins in February.

This is when sexual mature blue iguanas begin to prepare for copulation.

Grand Cayman iguanas are sexually mature between 3 and 9 years of age, while some faster growing iguanas become sexually mature by two and a half years.

In the wild, natural competition between males ramps up this time of year as they fight for their right to claim females. Males reassert dominance relationships, testing out who is the biggest and strongest, and expanding their range to try to monopolize as many female territories as possible.

According to BIC, when there is aggression, the majority of bite wounds are superficial and are mostly located on the head and nuchal crest, though bites can also occur on the fleshy body or tail. The BIC staff are on high alert to monitor breeding behavior, both at the facility and in the wild populations, to utilise opportunities for data collection and to intervene in the case that veterinary assistance is required.

When the female’s eggs are already formed and their abdomens are swollen, but before they are ready to become receptive to males, females keep well out of the way, retreating into their rock holes whenever the male(s) are around.

Throughout the breeding season the iguanas take on their most intense blue color. Males feed very little and lose weight, as they devote all their time to being dominant and breeding.

The females also cease feeding as their digestive tract is squeezed by the expanding mass of eggs.

Copulation begins with numerous head-bobs on the part of the male, who then circles around behind the female and grasps the nape of her neck. He then attempts to restrain the female in order to manoeuver his tail under hers to position himself for copulation which generally lasts from 30 to 90 seconds, and typically occurs no more than once and twice a day.

After copulation, the female becomes very territorial, aggressive and intolerant of all males, and chases them out of her territory. She becomes so aggressive that she will successfully run out males much larger than herself.

About six weeks after mating, she is ready to lay her eggs, and starts to burrow in the same area where she nests each year.

The female digs a nest cavity at least 1 foot deep in the sand and lays heir eggs. After depositing up to 20 eggs, she covers them with soil. The blue iguana’s eggs are among the largest laid by any lizard.

In captivity, the eggs are housed in incubators.

The eggs incubate at a temperature of about 86 to 91 degrees Fahrenheit (30 to 33 degrees Celsius), and the babies hatch 60 to 90 days later. BIC’s breeding facility produced more than 100 hatchlings in 2021.

When they are born, hatchlings are vulnerable to predation and have a high mortality rate. As a result, they are housed in a custom enclosure that is sectioned off from the rest of BIC.

In 2021, BIC was awarded a grant from Walkers Law Firm to go towards the construction of a new-look blue iguana nursery. BIC used the funds to build 54 new houses for young iguanas so that newly emerged hatchlings will be able to leave the incubator and live in safe, 8-foot tall enclosures with natural substrate, climbing areas and vegetation.

Hatchlings remain in the breeding facility for around three years until they are old enough to be returned to the wild.

In the wild, they generally survive for 25 to 40 years.

Given that it is currently breeding season, BIC asks all residents and tourists in Grand Cayman to take extra care when driving in Frank Sound, North Side and the East End- especially on Queen’s Highway. Blue iguana males are roaming to search for females and territories and may be sighted on or next to the roads.

Any concerns about blue iguanas can be directed to BIC by direct message on Facebook or Instagram or the National Trust office at 749-1121 or the Department of Environment at 949-8469.

Today, the breeding facility is home to approximately 100 Blue Iguanas of varying ages, many over five-feet long and in excess of 25 pounds. Due to the efforts of the programme, the Blue Iguanas were downgraded from the IUCN’s “red list” to endangered in 2012.

BIC’s major partners are Wildlife Conservation Society (WCS) at the Bronx Zoo and San Diego Zoo.