Red Eared Slider: A potential growing threat to Nepali Turtle fauna

The attraction of Nepalis towards keeping turtles as pets and the easy availability of the red-eared slider on online market stores requires attention of the researchers and policy makers. The red-eared slider is included on the list of the world’s 100 most invasive species, indicating these reptiles cause serious impact on biological diversity.

The red-eared slider (Trachemys scripta elegans) is a common semi-aquatic turtle native to North America. It is widely distributed across the globe mainly introduced through pet trade. It is a popular pet turtle across the world, and the popularity is often associated with their colorful appearance and relatively easy-care requirements. Aquarists find young red-eared sliders particularly appealing due to their small size and vivid color. But they grow rapidly into less attractive, aggressive large individuals requiring more space and other complex needs. 

They are very active and can escape from captivity and may also be released into nearby water bodies to get rid of the annoying pet after a while. These turtles have found their way to non-native water bodies when they escape accidentally or released intentionally by pet owners as they grow too large or become too difficult to care for. These turtles are known to outcompete native species as they can breed successfully in newer habitats. The process of invasion is supported by its characteristics of high fecundity, aggressive behavior, release of chemical cues and adaptability to new habitats.

As popular pets, the captive red eared slider can be found in various household aquariums, online marketplaces as well as in zoos in Nepal. This species is well established in wetlands such as Taudaha Lake in Kathmandu. The presence of red eared sliders was also noted in Chitwan according to a study. The distribution can be estimated to be wide as there is a lack of targeted studies on turtles in Nepal. Due to which the consequences caused by this exotic species on native turtle fauna of Nepal is unknown. The Nepalese turtle fauna consists of seventeen species and nineteen subspecies of native turtles. Of these, thirteen species are already listed in the threatened category by the International Union for Conservation of Nature (IUCN).

It is obvious that this exotic turtle species competes for resources like food, basking site and nesting site with the native turtles. Red-eared sliders are omnivorous feeders and feed on both the plant and animal matter. The juveniles mostly prefer more plant food while mature turtles, especially females consume more animal matter in their diet posing serious threat to native species. It was found that it prey on new hatchlings and juveniles of native species and causes the populations of native species to decline.  As observed in captivity they can victimize water birds and native turtles (Lissemys punctata, Pangshura tecta) which can be predicted due to their aggressive behavior. Trachemys scripta species are identified as the potential carrier of various parasites and pathogens including Salmonella. 

All the species of turtles found in Nepal are listed under Appendix I or Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Flora and Fauna). This means that the trade of native species is strictly prohibited and controlled. This exacerbates the import of exotic turtle species for household pets and market stores. There are many cases of rescue and confiscation of various turtle species by police from poachers and merchants. There may be presence of non-native species and the release of seized turtle species to natural habitats without proper protocols can be a threat to native turtles.

There is a lack of targeted studies and documentation  on the introduced faunal species, their impacts and invasive nature in Nepal. Likewise, there hasn’t been any documentation of red-eared slider turtles being established as invasive species in Nepal. However, they can be seen widely in captivity and occasionally being released into the wild. Being one of the worst invasive species in the world, the potentiality of red-eared slider turtles to become established in Nepalese freshwater ecosystems cannot be denied. Their high reproductive rate, adaptability to various habitats, and potential competition with native species for resources could lead to local extinction and ecological disruptions. When invasive species cause harm, it can be challenging and costly to manage and control. Preventing the introduction and spread of invasive species through careful monitoring and regulations is crucial for protecting native biodiversity and maintaining healthy ecosystems.