Stats
IUCN Status: Critically Endangered
Range: Little Cayman and Cayman Brac, Cayman Islands
Population: ~2,000–4,000
Size: Males: snout to vent length up to 2 feet, 24.3 pounds. Females: snout to vent up to 1.6 feet, 10.5 pounds
Threats: Habitat destruction from road construction and development; feral and free roaming cats and dogs; road mortality.
Species Information
- This Critically Endangered subspecies of Cyclura nubila is found only on Little Cayman and Cayman Brac, two small islands midway between Grand Cayman and Cuba.
- Because it is less developed, Little Cayman supports a larger population of Sister Islands Rock Iguanas, while Cayman Brac hosts an extremely reduced population of less than 200 mature adults.
- The Sister Islands Rock Iguana is one of the larger iguana species—some can be five feet in length and weigh 20 pounds, making a hefty impression. Males are larger and more aggressive than females and can get into some fierce tussles over territory.
- During breeding season in May, the females select an area that is suitable for nesting. Males roam widely and cross the territories of several females to breed with.
- Six weeks after mating, a female excavates a nesting burrow with an entrance tunnel and a larger egg chamber. She may lay 15 to 20 eggs at a time, and then fill in the nest and disguise it with leaves and grasses. She then guards the nest site for up to a few weeks to protect the eggs from potential predators and other females that may try to use the area for their own nest. The process is quite taxing for the females, which then need to feed and recover.
- After an incubation period of about 10 weeks, the baby iguanas start to hatch. Each hatchling gets nourishment from its egg sac, and the sisters and brothers wait until all have hatched, using their combined effort to dig their way out of the nest. Once they emerge, they head off on their own to make their way.
- Once abundant on both islands, the Sister Islands Rock Iguana has largely disappeared on Cayman Brac, suffering alarming losses to free-roaming dogs and feral cats. All populations are suspected to be in decline, with expanding island development exacerbating pressures of habitat degradation, predation by feral mammals, road traffic, and interaction with non-native species.
- In August 2016, a hybridization event between a male Sister Islands Rock Iguana and a non-native female Common Green Iguana raised new concerns about biosecurity on Little Cayman. The Little Cayman National Trust has been working diligently since 2012 to raise public awareness and eradicate the invasive Green Iguanas on Little Cayman.
- In 2012, the Little Cayman National Trust purchased a major communal nesting site on the west end of Little Cayman and began distributing “Iguana Crossing” signs at high traffic areas around the island in cooperation with the Cayman Islands Department of Environment, in order to warn motorists and try to reduce the number of iguanas lost to road strikes.
- Ongoing conservation efforts are aimed at raising public awareness, identifying remnant nesting sites, and evaluating the genetic health of the existing populations.
IIF Grants Received
2016 Grant $7,835
Population Trends and Age-dependent Survivorship in Cyclura nubila caymanensis on Little Cayman: an Ongoing Study in Conservation Biology
Jeanette Moss
$7,835
2015 Grant $9,150
Mark-recapture Study and the Use of Radio Telemetry to Investigate Nest-site Selection of Cyclura nubila caymanensis on Little Cayman
Jeanette Moss
$9,150
2014 Grant $4,350
Nesting Ecology of Cyclura nubila caymanensis on the Sister Islands, Little Cayman, and Cayman Brac
Jeanette Moss
$4,350