Demography and movement patterns of a population of eastern snake-necked turtles, Chelodina longicollis (Shaw, 1794)

With 226-343 individual/ha, population density of Chelodina longicollis in the dams of the University of Western Sydney-Hawkesbury Richmond campus were in the range of other studies around Australia. Their size extremes (24.3 -223.3 mm) were within the range of previous studies, and the overall sex ratio was skewed toward males. The annual growth rates varied and were weakly correlated with animal size. Scute shedding occurred between September and April and peaked in December. Turtles were generally in excellent condition, indicating that sufficient food resources were available in local habitats. Only 3.4% of the population were in poor condition and few animals (8.8 %) carried signs of past injury. No gross abnormalities were recorded, however, there has been low levels of recruitment to the population compared with other Australian studies. Despite a maximum distance dams sampled of 2.8 km and ample evidence of interchange between dams, there was a great variation in animal size, cohort structure, sex ratio among dams. There are a range of factors which have the potential to bias sampling results. Turtles were not influenced by a dominance hierarchy or by the presence of eels, however, they appeared to be capable of avoidance behaviour when nets are set at a specific location. Different cohorts were caught differentially and this varied with month, season and year. In addition, catchability varied among cohorts. Juveniles were least likely, and sub-adult males were most likely, to be recaptured. In some dams there was evidence that animals moved at random while in others movement did not conform to this pattern. These results could not be accounted for in terms of dam size, physical structure of the dam or the distribution and abundance of vegetation