A CONTINUED ASSESSMENT OF A TURTLE COMMUNITY IN THE CEDAR 
RIVER, IOWA

Andrew J. Huck and Gerald L. Zuercher
Department of Natural and Applied Sciences, University of Dubuque, 2000 University 
Avenue, Dubuque, IA 52001

In 2004, we initiated a pilot project at Ingawanis Boy Scout Camp along the Cedar River 
(Bremer County, Iowa) to assess the river turtle community.  This study was repeated 
during 2005.  In both years, wire turtle traps (Nichols Net & Twine Co., Inc., Granite 
City, Illinois) were opportunistically placed at a depth of no more than 1-m and baited.  
Trapping during the first year took place mostly on weekends between late-May and 
early-September 2004.  In 2005, we used a 10-day trapping session in May, June, July, 
and August.  Significant flooding events prevented trapping at certain times during each 
field season.  We captured 46 individual turtles representing 5 species in 2004; spiny 
softshells (Apalone spinifera; n = 19), snapping turtles (Chelydra serpentina; n = 11), 
painted turtles (Chrysemys scripta; n = 12), common map turtles (Graptemys 
geographica; n = 2), and false map turtles (Graptemys pseudogeographica; n = 2).    In 
2005, we caught 70 individual turtles, again representing 5 species; spiny softshells (n = 
43), snapping turtles (n = 10), painted turtles (n = 7), false map turtles (n = 9), and wood 
turtle (Clemmys insculpta; n = 1).  The wood turtle is an Endangered species in Iowa.  In 
our study, it was captured and released twice and all information was submitted to the 
Iowa Department of Natural Resources.  All turtles were weighed, measured, and marked 
by drilling a binary code on the posterior scutes with a Dremel® tool.  In 2004, many 
snapping turtles exceeded our capability to weigh them accurately; in 2005, new 
equipment was used in the field that provided accurate measurements of mass.  Several 
indices of diversity were calculated for 2004 and for 2005.  Diversity measures were 
consistently higher for 2004 except for Dominance (l) which was higher for 2005.  The 
turtle community in 2004 was compared with that of 2005 using three measures of 
community similarity, Sorenson’s (S), Morisita’s (CM), and Horn’s (CH) indices.  Each 
measurement suggested that community similarity between years was quite high.  
Morphological measurements for spiny softshells, snapping turtles, and painted turtles 
also are compared between years. 

Keywords:  Apalone spinifera, Chelydra serpentina, Chrysemys scripta, Iowa, Cedar 
River