COMMON SNAPPING TURTLE (CHELYDRA SERPENTINA) 
DEMOGRAPHICS

John K. Tucker
Illinois Natural History Survey, Great Rivers Field Station, 8450 Montclair Avenue, 
Brighton, IL 62012

The common snapping turtle (Chelydra serpentina) is commonly harvested as a food 
item in much of its range in the United States.  Much has been made of the potential 
impact of turtle trapping for local and export markets for this species and for other turtles.  
However, harvest of snapping turtles from roads has received little attention.  In many 
locations, snapping turtles are collected as they attempt to cross roads.  These turtles are 
nearly all females going to nest or returning from nesting.  A trapping program was 
initiated to examine the effect of incidental take from roads on snapping turtles in west-
central Illinois.  This project used three backwater lakes along the Illinois River as study 
sites.  Two lakes (Lower Stump Lake and Gilbert Lake in Jersey County, Illinois) extend 
along side Illinois Route 100, a rural road that is heavily traveled.  One lake (Swan Lake 
in Calhoun County, Illinois) is not near heavily traveled roadways, but is surrounded by 
the Two Rivers National Wildlife refuge.  The sites most exposed to human traffic were 
expected to have male dominated sex ratios compared to the more protected site.  
Preliminary studies have confirmed this.  Sex ratios at Gilbert Lake, the most exposed 
site, were found to be 90% male, whereas the most protected site (Swan Lake) had close 
to a 50% male/female ratio.

Keywords: common snapping turtle, Chelydra serpentina; Illinois River; demography.