J. Great Lakes Res. 33:791–805 Internat. Assoc. Great Lakes Res., 2007 791 * Corresponding author. E-mail: jleven@inhs.uiuc.edu Contaminant Exposure and Biomarker Response in Embryos of Black-crowned Night-herons (Nycticorax nycticorax) Nesting near Lake Calumet, Illinois Jeffrey M. Levengood 1,4,* , Luann Wiedenmann 2 , Thomas W. Custer 3 , David J. Schaeffer 4 , Cole W. Matson 5 , Mark J. Melancon 6 , David J. Hoffman 6 , John W. Scott 2 , Jonathan L. Talbott 2 , Gary O. Bordson 2 , John W. Bickham 7 , Barnett A. Rattner 6 , and Nancy H. Golden 6 1 Division of Ecology and Conservation Science Illinois Natural History Survey 1816 S. Oak St. Champaign, Illinois 61820 2 Illinois Waste Management and Research Center One Hazelwood Dr. Champaign, Illinois 61820 3 U.S. Geological Survey Upper Midwest Environmental Sciences Center 2630 Fanta Reed Road La Crosse, Wisconsin 54603 4 Dept. Veterinary Biosciences College of Veterinary Medicine University of Illinois at Urbana-Champaign 2001 South Lincoln Avenue Urbana, Illinois 61802 5 Integrated Toxicology and Environmental Health Program Duke University LSRC A346, Box 90328 Durham, North Carolina 27708 6 U.S. Geological Survey Patuxent Wildlife Research Center 12011 Beech Forest Road Laurel, Maryland 20708 7 Center for the Environment and Dept. of Forestry and Natural Resources Purdue University West Lafayette, Indiana 47907 ABSTRACT. We examined a suite of environmental contaminants and exposure endpoints in black- crowned night-heron (Nycticorax nycticorax, BCNH) embryos collected in 2002 from colonies in Illinois, Minnesota, and Virginia. Embryos from the Lake Calumet, IL, colony had greater exposure to polychlori- nated biphenyls (PCBs), 4,4′-dichlorodiphenyldichloroethylene (DDE), dieldrin, transnonachlor, oxy- chlordane, cobalt, copper, and selenium than did those from northwest MN and coastal VA. Embryos from IL and VA contained greater concentrations of mercury and zinc than those from MN, whereas the