Demographic response of snake-necked turtles correlates with indigenous harvest and feral pig predation in tropical northern Australia
Article first published online: 5 SEP 2007
Journal of Animal Ecology
Volume 76, Issue 6, pages 1231–1243, November 2007
How to Cite
FORDHAM, D. A., GEORGES, A. and BROOK, B. W. (2007), Demographic response of snake-necked turtles correlates with indigenous harvest and feral pig predation in tropical northern Australia. Journal of Animal Ecology, 76: 1231–1243. doi: 10.1111/j.1365-2656.2007.01298.x
- Issue published online: 5 SEP 2007
- Article first published online: 5 SEP 2007
- Received 12 November 2006; accepted 13 July 2007; Handling Editor: Graeme Hays
- age-specific fecundity;
- density dependence;
- juvenile recruitment;
- population regulation;
- wildlife utilization
- 1Species that mature late, experience high levels of survival and have long generation times are more vulnerable to chronic increases in mortality than species with higher fecundity and more rapid turnover of generations.
- 2Many chelonians have low hatchling survival, slow growth, delayed sexual maturity and high subadult and adult survival. This constrains their ability to respond quickly to increases in adult mortality from harvesting or habitat alteration. In contrast, the northern snake-necked turtle Chelodina rugosa (Ogilby 1890) is fast-growing, early maturing and highly fecund relative to other turtles, and may be resilient to increased mortality.
- 3Here we provide correlative evidence spanning six study sites and three field seasons, indicating that C. rugosa is able to compensate demographically to conditions of relatively low subadult and adult survival, caused by pig Sus scrofa (Linnaeus 1758) predation and customary harvesting by humans.
- 4Recruitment and age specific fecundity tended to be greater in sites with low adult and subadult survival (and thus reduced densities of large turtles), owing to higher juvenile survival, a smaller size at onset of maturity and faster post-maturity growth.
- 5These patterns are consistent with compensatory density-dependent responses, and as such challenge the generality that high subadult and adult survival is crucial for achieving long-term population stability in long-lived vertebrates such as chelonians.
- 6We posit that long-lived species with ‘fast’ recruitment and a capacity for a compensatory demographic response, similar to C. rugosa, may be able to persist in the face of occasional or sustained adult harvest without inevitably threatening population viability.