Irwin's turtle

 Elseya irwini is the second largest short necked turtle in Australia.  The mature females are known to have a distinctive pale yellow head and pink nose.   E. irwini was named by scientists in the 1990s, and is known only from the Broken River and tributaries downstream of Eungella Dam through to the Burdekin River.  Within the Burdekin River, known only from it's junction with the Bowen River upstream to about 18 km upstream of the township of Ayr (Lawler pers. comm.).  E. irwini is named after Bob and Steve Irwin (of Crocodile Hunter fame) (Cann 1997).

Very little is known about E. irwini.  Until Dr Ivan Lawler's pilot studies in 2006, the turtle had not been the subject of even the most cursory of ecological studies.  E. irwini occupies a river system over 100km in length and only two nests have ever been found.  Both of these nests were predated and no hatchlings survived.  It was recently nominated for endangered status under the Environment Protection and Biodiversity Conservation Act, because of the very low recruitment of juveniles into the population - population structure is very adult (93%) and female (91%) biased. Population modelling of other species in the genus suggests that juveniles should dominate the population. If juvenile recruitment does not increase, the population may collapse. Similar concerns have been the momentum for significant research and management action for a sister species, Elseya albagula, in the Burnett River in South East Queensland (Hamann et al. 2004; Hamann et al. in press).

As low recruitment is the major concern for this species, it is critical to rapidly develop an understanding of the location and preferred habitat for nesting sites, and nesting success at those sites. This requires that nest sites are identified so that monitoring can be undertaken.  To do so the research team will rely on the similarities between E. irwini and closely related species Elseya albagula and Elseya sterlingii.  E. albagula exhibits a tendency to aggregate at nesting banks with some individuals travelling up to 30km to reach these sites (Hamann et al. 2004). There is some evidence that a northern species of (E. sterlingii) also forms nesting aggregations (Turner 2004). Thus we expect E. irwini to exhibit similar behaviours.  Tracking of females that are soon to nest will enable us to rapidly identify key nesting sites within the core of their range.

Project Update

The James Cook University research team have returned recently from a field trip where a number E. irwini turtles were captured, transmitters attached and statistical information about the diet and biology of the turtles recorded.  The team will be returning regularly to the field to track the movement patterns of the nesting females and to identify key nesting sites.  By assessing the physical characteristics of these key nesting sites, we will gain a better understanding of the responses of the species to habitat modification.  The team will also be monitoring nesting success and survival of hatchlings, and identifying reasons for low juvenile recruitment.   

Useful resources

Freshwater turtles

Bells's turtle , Elusor macrurus

Fitzroy River turtle , Rheodytes leukops

Gulf snapping turtle , Elseya lavarackorum

Irwin's turtle , Elseya irwini

Johnstone River turtle , Elseya sp. ( Johnstone River )

Mary River turtle , Elusor macrurus

White-throated snapping turtle , Elseya albagula 

Marine turtles

Flatback turtle , Natator depressus

Green turtle , Chelonia mydas

Hawksbill turtle , Eretmochelys imbricata

Leatherback turtle (leathery turtle) , Dermochelys coriacea

Loggerhead turtle , Caretta caretta

Pacific ridley turtle (olive ridley) , Lepidochelys olivacea

Turtle species identification

References

Cann J. 1997. Irwin's Turtle. Elseya irwini sp. nov. Holotype Q.M. J59431 collected by J. Cann, October 1993.  Monitor (Victorian Herpetological Society, Melbourne ) 9(1): 36-40, 31-32.

Cann J. 1998. Australian Freshwater Turtles. Beaumont Publishing Pty. Ltd . , Singapore .

Georges A, Thomson S. 2002. Evolution and Zoogeography of the Australian Freshwater Turtles. In: Merrick JR, Archer M, Hickey G, Lee M, eds. Evolution and Zoogeography of Australasian Vertebrates. Sydney : AUSCIPUB (Australian Scientific Publishing) Pty. Ltd.

Hamann M, Schauble C, Emerick S, Limpus C, Limpus D.  2004.  The Burnett river snapping turtle, Elseya sp. [Burnett River], in the Burnett River Catchment, Queensland, Australia: Biological Report.  In. Wildlife Ecology Unit, Environmental Sciences Division, Environmental Protection Agency, Queensland, Brisbane.

Hamann M, Schauble CS, Emerick S, Limpus CJ, Limpus D.  (in press).  Freshwater turtle populations in the Burnett River.  Memoirs of the Queensland Museum.