Nesting Behavior of the Pig-Nosed Turtle, Carettochelys insculpta, in Australia

We studied the nesting behavior of the pig-nosed turtle, Carettochelys insculpta, in northern Australia. We used remote camera systems and focal observations to test the hypothesis that the nesting behavior in C. insculpta is similar to that of its closest relatives, the softshell turtles (Trionychidae). Carettochelys nested at night, in contrast to diurnal nesting in the majority of softshell turtles. Observations of groups of turtles in the water prior to nesting indicated gregarious or social behavior. On average, gravid turtles emerged around 6 times onto 1-2 beaches spanning 2 nights. Turtles nested at around 2100 ± 3 h, when sand temperatures at nest depth were near their maxima. Minimum air and water temperatures during nesting were 17.5oC and 24.6oC, respectively. Nesting turtles spent an average of 27 min on a beach, similar to softshell turtles but shorter than reported for most other turtle species. Relatively short nesting duration in these species may be caused by the ease in excavating a chamber in sand and the close proximity of nesting areas to water. Overall, the nesting sequence reflected the conservative nesting behavior in turtles, was similar to that of softshells, but differed in subtle ways. Empty nest chambers, commonly referred to in the literature as "test holes", were sometimes the result of abandonment resulting from incidental contact between turtles searching for a nest site.