Abstract
Freshwater turtles are one of the most endangered vertebrate groups, with an estimated 60% of species threatened. The influence of environmental factors on the life cycles of most turtle species is poorly understood, including triggers for nesting movements. Although temperature and rainfall have been identified as triggers for nesting in some species, it is unknown if and how reductions in rainfall arising from climate change may disrupt reproductive movement. We aimed to determine the environmental factors that trigger nesting movements of Southwestern Snake-necked Turtles (Chelodina oblonga) in south-western Australia, a global biodiversity hotspot undergoing severe climatic drying. A citizen science program was implemented to monitor nesting behavior over a 4-yr period. Generalized linear mixed models (GLMM) were used to identify the environmental variables that best explained the number of female turtles exhibiting nesting movements. Daily nesting movements were significantly associated with decreasing average air pressure, consistent with seasonal cold frontal weather systems that bring the majority of annual rainfall to the region. The effect of rainfall on turtle nesting movements varied depending on the spatial scale of modelling. Our results indicate that the projected reductions in frequency of cold fronts and rainfall in southwestern Australia may disrupt nesting movements. This could reduce recruitment success of this turtle and further increase the need for adaptive management to improve conservation of the species. The study highlights the need for further research on the impacts of climate change on environmental triggers of nesting of freshwater turtles in drying regions.