The Flatback Turtle, Chelonia depressa, in Queensland: Reproductive Periodicity, Philopatry and Recruitment

Abstract

The Bundaberg coast is the southern limit for reproduction by Chelonia depressa in eastern Australia. Here the species lays 2.84 ± 0.78 (mean ± SD) clutches per breeding season with a renesting interval of 15.99 ± 1.89 days. When successful nesting does not occur on a nesting crawl the female returns after 1.17 ± 1.07 d for another attempt. The mean remigration interval is 2.65 ± 0.92 years and the average female is estimated to have a reproductive life of between 2.05 and 2.55 breeding seasons. The estimated annual recruitment rate of neonate nesting females into this colony is 27.2 ± 10.8% of the population. The females return repetitively with a high degree of accuracy to the same small nesting beach within a single breeding season and in successive breeding seasons. The reproductive strategy of C. depressa compared with that of other sea turtles appears to involve an increase in hatchling size, to reduce predation, achieved by laying relatively large eggs. However, only a few small clutches are laid in a breeding season, so that seasonal fecundity for the species is low relative to that in other sea turtles such as C. mydas. Because its reproductive life is longer, C. depressa has a total fecundity only slightly less than that of C. mydas.