Red-eared slider turtle

What does it look like?

Why is it a problem?

Adult turtles can become aggressive and will attack species larger than themselves. They are known to take over nesting sites of water birds. Red-eared slider turtles are classified as one of the “World's Worst Invasive Alien Species” by the World Conservation Union's (IUCN) Invasive Species Specialist Group.

Sexual maturity appears to be size dependent: males mature at a carapace length of 10 cm, and females mature at 17 cm. Females can retain sperm and produce offspring up to five years post insemination. Typically, they lay 2–3 clutches per breeding season, though more are possible. Clutch size usually ranges from 4 to 15 eggs, with records of up to 23 eggs per clutch in South Africa.

Successful incubation requires soil temperatures between 22-33°C and takes between 55-80 days. Temperature determines hatchling sex: cooler conditions (27°C or below) tend to produce all males, while warmer conditions (around 30°C or higher) produce all females. Despite these incubation conditions, significant variability in sex ratios may occur between clutches from different females. Females may roam several hundred metres or even several kilometres from water bodies to locate suitable nesting sites, with eggs sometimes buried as deep as 140cm deep. Juvenile mortality is often high due to predators such as birds, though survivors tend to grow rapidly.

Wild populations are frequently supplemented by individuals from the pet trade. Unwanted adults are often released into the wild by owners, and some turtles may escape or wander off on their own. Females are more frequently reported as lost/found, therefore if male-biased reproduction occurred in the wild inputs from the captive population would likely at least partially adjust the sex ratio.

Control methods

If you have seen or suspect the presence of Red-eared slider turtle you must report the sighting to us immediately.

We may undertake direct control of wild red-eared slider turtles. Landowners/occupiers are encouraged to report any sightings of wild red-eared turtles on their properties. These turtles should only be sold by pet shops and should be kept securely by pet owners and not released elsewhere.

Do not release unwanted turtles into the wild. This is an offence under the Biosecurity Act.

More information

Their diet is omnivorous, including vegetation (all plant parts), zooplankton, molluscs, frogs, crustaceans, insects, gastropods, birds and small reptiles. Diet composition varies with age, location and food availability.

They are generally visible during the day and inhabiting a wide variety of still or slow-moving water bodies including ponds, lakes, wetlands, rivers (including brackish reaches and salt marshes), and drainage ditches. They are capable of rapid range expansion via overland dispersal and may seasonally use varied terrestrial habitats including golf courses, farmland and forest. They prefer temperatures between 25-29°C but can withstand much colder temperatures. Adults can survive extended periods at -10°C. Juveniles are more sensitive to cold temperatures and may die at -0.6°C, although overwintering in nests can provide some protection from freezing temperatures. Red-eared sliders are pollution tolerant.

Related links

https://www.doc.govt.nz/globalassets/images/nature/pests-and-threats/animal-pests/red-eared-slider-turtles/slider-turtles-poster.pdf