Common name: Irwin's turtle
Scientific name: Elseya irwini
Family: Chelidae (side-necked turtles)
Conservation status: This species is listed as Least concern in Queensland (Nature Conservation Act 1992).
This is a large short-necked turtle with a carapace (upper shell) over 330mm in length (width 260mm). There are two separate, genetically distinct populations: one is confined to the Johnstone River in the Wet Tropics and the other is confined to the Burdekin River. Adult female Burdekin E. irwini are distinguished from all other Elseya in having pale yellow colouration on the head that extends to the top of the crown. Irwin’s turtles from the Johnstone River only have white or cream colour on the throat and sides of the head, as also seen in many other Elseya species. Both Burdekin and Johnstone River adults can also have distinctive pink noses. In the two river catchments where this turtle occurs, E. irwini will always attain a larger size than any other short-necked turtles present.
Habitat and distribution
Irwin's turtle is known from the Burdekin catchment (which includes the Bowen River) in North Queensland and the Johnstone River in far North Queensland. It was first discovered in the Burdekin catchment by Steve Irwin and his father Bob in 1990. In the Johnstone catchment it had been known since at least the 1970s, when it was called the northern snapping turtle (Elseya dentata).
Behaviour and life history
These turtles will often bask on exposed rocks and logs and commonly float with just their heads breaking the surface of the water. At night they have been known to emerge into shallow riffle zones to feed on algae that cover the boulders. Irwin’s turtles lay their eggs in nests that have been dug into river banks, with nesting occurring anywhere between April and July. In common with other ‘snapping’ turtles, adult Irwin’s turtles are mainly herbivorous. Both male and female turtles show a strong preference for leaf matter and stems sourced from terrestrial riparian vegetation. Fruit, algae, aquatic plants and non-native pasture grasses (when flooded) are also consumed but seemingly in smaller proportion to leaf material. Animal matter such as shrimp, molluscs, aquatic insects and carrion are also consumed but are probably not as important for adults in the wild. Juveniles tend to be less herbivorous and more carnivorous than adults. In captivity Irwin’s turtle will eat fish and raw meat as well as vegetable material.
A number of potential threats have been identified, although little information is available on the degree and extent of these threats. To date, habitat loss and degradation, nest predation and disturbance by feral predators (mainly pigs) and pollution are considered important threats.
While more information is still needed on distribution, abundance and the threats facing Irwin’s turtle, some work has begun. The Threatened Species Unit of the department has been collecting data on this turtle in the upper reaches of the Johnstone River to guide conservation management of this turtle into the future.
What can be done to help this species?
The most important thing that can be done to help this species is to preserve intact native riparian (riverside) vegetation. This one act will help maintain water quality, nesting banks and food for this species. In addition to this, fencing of nesting banks and feral animal control may be appropriate in some situations.
Any sightings of 'white-headed turtles' in the Burdekin and Johnstone drainages should be reported to the Threatened Species unit of the department. Contact Alastair Freeman at Alastair.Freeman@des.qld.gov.au or the WildNet team at WildNet@science.des.qld.gov.au.
Related information Cann, J. (1998). Australian Freshwater Turtles, Beaumont Publishing.
Cann, J. (2008). A Wild Australia Guide. Freshwater Turtles. Steve Parish Publishing.