A comparison of sample and total census data for a population of the Eastern Longneck Turtle Chelodina longicollis in a farm dam north-west of Sydney, New South Wales

Interpretation of trap bias in sampling freshwater turtles has previously relied on indirect methods. The data presented here provides the first comparison of a sample and total census of a waterbody. Eastern Longneck Turtles Chelodina longicollis Shaw were sampled in a 0.1 ha farm dam for three days immediately prior to drainage and a population census was subsequently carried out. Fyke nets proved to be an effective method of sampling the population. During the sampling phase 78% of males (n = 11) and 81% of females (n = 21) were captured, and there was no significant difference between the sample and the census in terms of population size structure (χ23 = 1.12, excluding juveniles) or sex ratio (χ21 = 0.008). None of the three resident hatchlings were captured despite a high probability of capture (p = 0.67). Hatchlings and juveniles combined made up 19.4% of the population and there were no immature resident females and few immature males. Based on the population profile, recruitment was intermittent and apparently infrequent with the greatest cohort being mature females, although there were no immature females. Mature males were present in larger numbers than immature males.