enter extended periods of aestivation until rain occurs and water levels increase. Reproduction C. expansa usually nests during Austral autumn or in early winter when soils decrease in temperature. It will also sometimes nest during spring. Although the female broad-shelled river turtle will travel up to one kilometre away from the bank to lay her eggs, it is more common for them to nest within 100 m of the water's edge. Along the Murray River, nests are often constructed at the top of sandy ridges. In Autumn nestings, temperatures in the nest will initially decrease and then remain low during the winter period before slowly increasing during spring to reach a maximum temperature during summer. The female turtle constructs a nest by excavating a nesting chamber with her hind legs to a depth of around 20 cm. She then deposits between 5 and 28 eggs before backfilling the nest with soil. The broad-shelled river turtle has shown a ‘body-slamming’ type behaviour when compacting nests. This behaviour results in the formation of a hardened 'plug' which helps to seal the nest. These turtles will nest any time of the day or night with nesting being initiated by rain. Turtles tend to select nest sites that have higher sun coverage. The selection of nest sites is often a long way from the waters edge and this is seen as a behavioural strategy to minimise the risk of nest flooding. Hatchlings are exposed to a number of challenges. Incubation is exceptionally long due to inherently slow embryonic development, averaging between 324 and 360 days. Development is also delayed when the embryo enters two distinct periods of diapause. The primary diapause occurs inside the female before the eggs are laid. This form of diapause is known as pre-ovipositional embryonic arrest and is found in all turtles. The secondary diapause is triggered by a drop in nest temperature and occurs after embryonic growth has resumed within the nest. The young will generally hatch during spring. Asynchronous hatching is most likely maladaptive in the natural environment. Upon hatching, the young remain in the egg chamber awaiting heavy rain to trigger their release. The soil surrounding the nest, which becomes compacted and relatively hard during the long incubation, is softened by the rains and allows the hatchlings to dig their way out through the softened soil. Diet The broad-shelled river turtle is highly specialized and entirely carnivorous.