Urban hazards: spatial ecology and survivorship of a turtle in an expanding suburban environment

Urbanization poses a threat to long-lived vertebrates, particularly from road mortalities that can threaten population persistence. We studied movements, behavior and survivorship in a semi-aquatic turtle, Chelodina longicollis, during a La Niña period of above average rainfall (wet period) from 2012 to 2013. Our goals were to compare female turtles in a suburban environment to those in an adjacent nature reserve, and to interpret our results relative to a previous study in the same system during an El Niño period of drought from 2006 to 2007. During the wet period, turtles from suburban and nature reserve environments exhibited largely similar movements and use of space, and turtles did not aestivate terrestrially despite prolonged periods of aestivation during the 2006–2007 drought. Additionally, turtles from suburbs had reduced annual survivorship (0.67) compared to turtles in the nature reserve (1.00) during the wet period, which contrasts with previous estimates during drought, when survivorship did not differ between environments. Such a reduction in survivorship for suburban turtles resulted largely from vehicular collisions and may be a consequence of rapid increases in human population (79 %) and traffic volume (76 %) over the eight-year study period. Our study demonstrates that turtle behavior and survivorship can be variable in space and time, and that both urban development and climatic conditions can interact and change relatively quickly to influence important aspects of turtle behavior and population biology.