Joan R. CallahanJOAN R. CALLAHAN is an environmental scientist who has served as a consultant to many environmental engineering firms, land developers, and government agencies, including the U.S. Geological Survey Biological Resources Division, the National Institut for Environmental Health Sciences, and the California Parks and Recreation Department. She is also an award-winning author of several science and engineering books, as well as numerous scientific papers and environmental documents. Dr. Callahan holds a Ph.D. in Zoology from the University of Arizona.
Read More Read Less