CLIMATIC WARMING AND RED-EARED SLIDER (TRACHEMYS SCRIPTA ELEGANS) NATURAL 
HISTORY  

John K. Tucker1, Chad R. Dolan1, James T. Lamer1, and Emily A. Dustman2

1 Great Rivers Field Station, Illinois Natural History Survey, 8450 Montclaire 
Avenue, Brighton, Illinois 62012-2032, USA 
2 Department of Biology, Southern Illinois University at Edwardsville, 
Edwardsville, Illinois 62025, USA  

Average annual temperatures for Jersey County in west-central Illinois have 
shown a remarkable upward trend.  Since 1992 the rate of increase has been 0.16 
degrees C per year.  The Red-eared Slider (Trachemys scripta elegans), a large 
emydid turtle with a wide distribution in the southern United States has a 
complex natural history.  We present a medium-term study conducted between 1994 
and 2006 that demonstrates an equally remarkable pattern of response from the 
turtle to these climatic events.  Turtles are shown to be nesting earlier in the 
year, laying more eggs each year, and producing hatchlings that have male-biased 
sex ratios.  Increase reproductive output and male-biased hatchling recruitment 
are shown to be having a profound effect on demography in river backwaters of 
the Illinois River.

Keywords: Climatic warming, Illinois River, Red-eared Slider, Trachemys scripta 
elegans, sex ratios