Abandoned turtles and terrapins; the impact they have on our native wildlife and the suffering they endure when left out in the cold.
Pet turtles and terrapins have been regularly abandoned by their owners for decades in various ponds, rivers and canals in the United Kingdom, but despite a relatively large amount of research into the subject and the cruelty of the act, this trend continues. Perhaps this is the case, as when people buy a tiny terrapin at the pet shop when it is not much bigger than a fifty pence coin, they are often assured buy the sellers at the shop that it won’t get much bigger than that. Alternatively, maybe it is because once the said pet reaches the size of a small dinner plate, it is easier to convince oneself that you are doing the animal a kindness by releasing it into the wild, rather than committing oneself to the expensive and time consuming care that these exotic animals require. Most likely, the reason this trend continues is because people are genuinely unaware of the negative effects of the terrapin on the local environment and the distressing circumstances the animal will quickly find itself in.
Abandoned terrapins in British waters are almost always going to have their welfare compromised from the start, both in terms of health and chances of survival. The estimated annual mortality for feral terrapins and turtles in the UK is thought to be between 40-80%.
Terrapins require specific water temperatures, a good depth and flow of oxygenated water in their habitats and basking areas orientated towards the sun, not to mention good accessibility to suitable food. Furthermore, as terrapins like all reptiles are cold blooded, if they are released into an area with a lot of shade, such as tree lined banks of a canal, or a pond in a wood, they can really struggle. In cool areas, terrapins may be unable to get their body temperature high enough to move around, let alone eat and digest food. When the temperature drops below 16-18 degrees Celsius, they will not forage for food at all. This means for the majority of the year in the UK, they will be unable to forage and if there is a cold summer, they will be unlikely to build up enough fat stores to survive though hibernation.
Even in captivity, terrapins are complex and long-lived pets to maintain and often need to be supplemented with vitamins, as well as enough UV light for them to synthesise vitamin D3, which helps them absorb calcium from their food. Without supplements or enough sunshine or UV light, terrapins both feral and in captivity can suffer from ailments such as shell rot, which results in a weak and spongy shell. Vitamin A deficiency can result in swollen eyelids in terrapins which means they eventually fuse together, making them blind and unable to feed. The general cold climate of the UK means that the immune system of these animals, which are almost all adapted to the tropics or sub-tropics, is often compromised and that they are more prone to disease, such as respiratory problems and hypothermia. Inevitably, this means that the health of a large proportion of terrapins and turtles that are abandoned quickly deteriorates and they often end up and diseased or slowly starving to death.
Aside from the obvious ethical implications of abandoning terrapins and turtles, the relatively little research on them that has been done suggests that they may also have negative impacts on the environment. Though terrapins are omnivorous, they primarily eat plants, though will opportunistically take invertebrates and small mammals where they can get them. Where terrapins are released into small ponds, or where a large number of them are present, they can over consume vegetation in the pond. This may seem trivial, but not only does this mean they exhaust their own food source, but pond plants also play a vital role for our native wildlife. Newts, including the protected great crested newt, rely on plant leaves to fold over and lay their eggs in. Dragonfly and other invertebrate larvae, in addition to tadpoles, also depend on pond plants to shelter from predators, but also for food as they eat the algae that grows on them. Water fowl often make nests in and amongst plants along the margins of ponds and these areas are also important foraging and resting places for other wildlife, such as grass snakes. On a larger scale, when there is a reduction of oxygenating plants in the pond and an increase in nutrient input (for example from the faeces from a group of terrapins in a small pond), this can result in the eutrophication of the water. Eutrophication then means that the oxygen is so depleted in the pond that only organisms that can survive in oxygen poor environments, such as algae, persist. As terrapins are thought to be opportunistic feeders, they may also be directly impacting animal populations by eating invertebrates, amphibians and their larvae and possibly even young birds. To make matters worse, if a terrapin is abandoned in an urban park surrounded by roads, it is likely it will have no other ponds to go to, so it will continue to deplete the pond of its wildlife whilst it struggles to find enough to eat.
The release of non-native herpetofauna (reptiles and amphibians) has been increasing and many of these animals can also carry diseases that can be spread to our native wildlife. Though this is primarily a concern with the two chytrid fungus species being spread by invasive or exotic amphibians as well as ranavirus infection which has caused substantial mass mortality in common frogs in England, terrapins have been documented to spread the Hexamita protozoan to birds before.”
Unfortunately, at least 4000 terrapins are thought to be feral in the UK and rescues are struggling to keep up. London is the densest area for terrapin abandonment. In addition to this, it can be very difficult to catch and remove terrapins once they have been released. Abandoning terrapins is not only illegal, but cruel and not only does it cause suffering to the animal, but it often damages local ecosystems. Non-native species that are present in the UK are estimated to cost UK economy £1.7 billion per year. More research needs to be done into the effect of feral terrapins on the environment and awareness needs to be raised to prevent the illegal release of them.
(Alexia Fish, London Dragon Finder Ecologist)
Langton and Herbert, 2011. On the distribution, ecology and management of non-native reptiles and amphibians in the London Area. Part 1. Distribution and predator/prey impacts. The London Naturalist. No. 90, pp.83-156
Langton and Herbert, 2011. On the distribution, ecology and management of non-native reptiles and amphibians in the London Area. Part 2. Disease impacts, perspectives, trade exploitation and finding ethical solutions. The London Naturalist. No. 90, pp. 157-178