Little Cayman biodiversity flourishes with invasive species controls

A previously untouched haven for native species and virgin habitat, Little Cayman has been exploring the potential benefits of invasive species controls for nearly two decades. As steep declines in annual populations of the Sister Islands Rock Iguana – found only in the Sister Islands and nowhere else in the world – were consistently recorded, cameras placed out in the wild, along with iguana remains showed clear evidence of cat predation, particularly on hatchling, young, and sub-adult segments of the population. In response, a partnership was formed between the Department of Environment, the Royal Society for the Protection of Birds (RSPB) and the National Trust for the Cayman Islands, supported by UK Darwin Plus funding, with a mandate to control feral cat populations living in the wild, promote responsible pet ownership among the community and develop biosecurity protocols with local stakeholders to help secure the sister islands from invasive species arriving undetected in cargo.

Now, after just two years of control work, it’s estimated that approximately 87% of invasive feral (unowned) cats have been removed from the natural environment and many Little Cayman residents say they have noticed a significant increase in the number of young Sister Islands Rock Iguanas and other native wildlife including Curly-tailed lizards, birds, butterflies, and the Little Cayman anole, also endemic to the island and found nowhere else in the world.

In addition to the significant impacts feral cats pose to native wildlife, a DoE study of the health of feral cats removed from the environment between 2022 and 2024 revealed poor body conditions from starvation, pregnancies, injures and infections with many having mature parasites and trash matter within their digestive tracts.

In 2023, after the first year of control work showed signs of biodiversity recovery, a team of invasive species eradication experts from Australia were invited by the DoE to visit Little Cayman and conduct a preliminary study on the feasibility of eradicating feral cats entirely from the island. With its small land mass and relatively low human population, the study showed it was indeed feasible, though experiences on other islands similar to Little Cayman indicate that a variety of methods are needed in order to ensure its success.

In late November 2024, a public meeting was held at the Little Cayman Beach Resort hosted by the DoE’s Terrestrial Resources Unit (TRU), and led by TRU Manager Frederic Burton, to report the increasing Sister Islands Rock Iguana population data and gauge community interest in taking the project further. Many residents indicated support for the preservation of Little Cayman’s native and endemic species, particularly the Sister Islands Rock Iguana, and confirmed that eradication of all feral, unowned cats living in the wild would be a massive step for biodiversity conservation in Little Cayman.

The Australian team has returned to Little Cayman this month to perform tests using humane, non-lethal, unarmed trap and non-toxic bait methods which have proven successful in other cat eradication projects, to help determine if non-target, native species might be impacted by them. A non-lethal, humane, soft-clamp leg-hold trap, and a suspended non-toxic bait lure will be tested in the environment over the next 4 weeks – but not actually armed or enabled, so leg traps will not close and baits will be non-toxic.

Motion cameras will record any species which interact with the setups so its safety and efficacy can be determined before any decisions to move forward with the project are made. These deactivated, testing traps are solely for the purpose of studying how Little Cayman’s native species will react to them and will help determine if iguanas, birds or land crabs, for example, are attracted to the non-toxic test bait to help inform adjustments if needed and ultimately, whether the techniques can work safely in Little Cayman’s ecosystem, illuminating harm to non-target species. The testing traps will be clearly marked and pose absolutely no threat to humans or pets.

Eradication (or even extensive control over wide areas) is not currently being explored in Grand Cayman or Cayman Brac as these areas are much more densely populated and complex.

Depending on how the tests go, a new conversation with the community about the possibility of eradicating all feral cats from the delicate island ecosystem of Little Cayman will emerge. It is only with community support across the islands that our unique biodiversity might be preserved and protected from the impacts of invasive predators.

Learn more at www.conservation.ky/invasive-evidence

WATCH the videos to learn more about the Sister Islands Partnership project and protecting native wildlife in the Cayman Islands from the severe impacts of invasive predators.