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

Abstract

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 ...