December 2016

Strange Turtle Behaviour?

Several months ago I found a turtle beside the path churning up the mud. Is it a native species and what was it doing?

Answer

The nesting behaviour of Broad-shelled Turtles.
Image Credit: Kate Bilston
The nesting behaviour of Broad-shelled Turtles.
Image Credit: Kate Bilston

This is an native Broad-shelled Turtle (Chelodina expansa). This is Australia’s largest freshwater turtle with a shell length of around 48cm, although when the neck is extended the whole animal can be as long as 80cm. You are very lucky to have seen one of these turtles as they are quite secretive and seldom emerge onto land. This particular turtle is a female and is excavating a nest, which is one of the very few reasons she will move any distance from water.

The hole she digs will be around 15cm deep and flask shaped (narrow at the top broader at the bottom).She will deposit anywhere between 10 and 20 hard shelled eggs, then cover them up and return to the water. During unfavourable times such as dry or cold weather the newly hatched young may wait many months in the nest (200-600 days) and finally escape when rain softens the surface soil allowing them to dig their way free.

They are capable of holding eggs inside their body for some weeks if they cannot readily access a suitable nesting site. This species nests from autumn to winter and will emerge to nest during or immediately after good rain. These turtles often dig nests in pathways or walkways through bush as the ground is generally flattened and void of grass or foliage roots that may form mats over the surface. The hatchlings will dig themselves out during the warmer seasons and make their way straight to the water.

 

Queensland Museum's Find out about... is proudly supported by the Thyne Reid Foundation and the Tim Fairfax Family Foundation.