Krefft's Turtle

Introduction

This species of short-necked turtle was described by Dr J. E. Gray of the British Museum of Natural History in 1871. The first specimens were collected from the Burnett River in south-east Queensland by the Australian Museum under the then curator Gerard Krefft, who later forwarded them to the British Museum. The species was therefore named by Dr Gray Chelymys krefftii in honour of Krefft.

Identification

This short-necked turtle is the only species of freshwater turtle east of the Great Dividing Range that has facial stripes, which are bright to pale yellow in colour and extend back from the eye to the ear (tympanum). The shell is deep and oblong-shaped, with an olive-brown to blackish-brown carapace and blueish-green tinged plastron underneath (a distinctive feature of this species).

Habitat

Larger permanent rivers and swamps, as well as river overflows and lagoons. Typical habitat has reeded areas for young to hide when resting. Adults will bask on exposed logs and rocks above the water.

Distribution

This species occurs only in Queensland within the drainage systems of the eastern side of the Great Dividing Range, from Brisbane to Princess Charlotte Bay.

Seasonality

In the Burnett River in Queensland, Krefft’s Turtles have been observed actively foraging in winter (July-August), and in captivity these turtle can remain active in winter temperatures as low as 11-14º C.

Feeding and diet

Krefft’s Turtles are completely carnivorous as hatchlings and juveniles, feeding on aquatic insects and larvae, crustaceans, small fish – almost any source of protein, including carrion. As the turtles mature they become more omnivorous, feeding on aquatic plants as well as fruits from over-hanging vegetation, while still hunting for live prey and eating any kind of meat they may find in the river.

In captivity, hatchlings feed on whole and chopped earthworms. At the Australian Museum adults are fed whitebait, prawns, kangaroo mince, chopped green vegetables as well as a mix of cauliflower, carrot and sweet potato. This is supplemented with dry cat food kibble as well as vitamin and calcium powder.

Other behaviours and adaptations

During times of drought, this species may be encountered crossing roads in search of more permanent bodies of water.

Adults groom by scratching the head and neck with the front legs as well as scratching the inside of one rear leg with the claws of the other rear leg.

Observations made by divers suggest that the turtles use fallen trees, root tangles and large stands of submerged aquatic vegetation as refuges. In the wild, adults can often be seen basking on emergent logs. In captivity, the young will leave the water to bask under a heat light. At the Australian Museum adult turtles are observed sleeping on the bank at night and will spend large amounts of time on the bank during waking hours.

Breeding behaviours

Courtship (and presumably mating) in wild Krefft’s Turtles begins in autumn, with nesting taking place between October and January throughout its range. Wild females taken from the Burnett River were found to contain both oviducal eggs and large ovarian follicles simultaneously, suggesting that they may be capable of producing more than one clutch per season. Multiple clutching in captivity is known – a couple of females laid two clutches of eggs in one “season”, with the interval between the two clutches being 51 days for one female and 74 days for the other.

Nests are excavated away from the water’s edge, and up to 16 eggs are laid per clutch. The eggs are white, hard-shelled, and measure around 33 x 21mm and weigh approximately 7g. Incubation periods range from 45-74 days at temperatures ranging from 18-30°C. After first rupturing their shells, the hatchlings may stay in their eggs for 12 to 48 hours, before quickly digging their way out of the nest chamber. Hatchlings measure between 27-31.8mm in shell length and 24-29.5mm in shell width, and weigh from 3.6-5.1g. They may begin eating almost immediately after hatching, or delay this for up to two days.

Predators

The hatchlings are occasionally eaten by Spotted Barramundi Scleropages leichardti, and Mulga Snakes Pseudechis australis. Juveniles are sometimes taken by catfish, and adults may be dragged from the water and eaten by Water Rats Hydromys chrysogaster.

The species' known parasites include fluke worms and round worms.

Management

This species is protected in Australia and cannot be collected from the wild and a permit is required in most states and territories to keep this species in captivity. Please check with your local wildlife licensing agency.

References

• Cann, J. 1998. Australian Freshwater Turtles. Beaumont Publishing. Singapore.
• Cogger, H. G. 2000. Reptiles and Amphibians of Australia. Reed New Holland, Sydney
• Ehmann, H. 1992. Encyclopaedia of Australian Animals: Reptiles. Angus & Robertson. Pymble.
• Greer, A. E. 2006. Encyclopedia of Australian Reptiles : Chelidae. Australian Museum