The endangered Sister Islands Rock Iguana population has been in steep decline for years, as shown by surveys which started in 2014. In response to calls from the Little Cayman community and evidence of predation on young iguanas, the Department of Environment began controlling feral cats in 2022, supported by a Darwin+ grant through Biodiversity Challenge Funds & RSPB. After removal of most of the feral cats on the island, the rock iguana population on Little Cayman has more than tripled in three years, from a low of about 1,000 individuals in 2022 to about 3,500 in 2025. This inspiring recovery gives us new hope for Little Cayman’s iguanas.
The most recent survey was conducted from 4 – 14 March 2025. Two teams of two people each surveyed 118 transects across Little Cayman. Each transect is 200 m long and is grouped into segments to allow for efficient movement between transects during the survey. Observers recorded the distance to each SIRI detection made in a transect, the age of the iguana (hatchling, under six months old; sub-adult, one to three years old; and adults, more than three years old).
Estimates of the Sister Islands rock iguana (C. n. caymanensis) population in Little Cayman from 2014 – 2025. Points are mean estimates and error bars represent 95% confidence intervals.
The increase in the hatchling and sub-adult age classes in 2025 continues to provide evidence that reducing the feral cat predation pressure through removal trapping in 2022 – 2024 has had a positive impact on hatchling survival in the 2023 & 2024 hatchling emergence seasons.
In addition to this important work, the Little Cayman community have rallied together to ensure 100% of domestic pet cats are microchipped, vaccinated and desexed – the first of the Cayman Islands to achieve this critical milestone – eliminating the causal link between pet cats and the feral population. This was achieved through the active community support in partnership with the Department of Environment, National Trust for the Cayman Islands, Cayman Islands Humane Society and the Cayman Islands Department of Agriculture – bringing vet services and support to pet owners on the island.