Erwin E. "Irv" Klaas was born on August 23, 1935, in Batchtown, Illinois. He graduated from Elsberry (Missouri) High School in 1952. Klaas received his B.S. (1956) in wildlife biology from the University of Missouri and his M.A. (1963) and Ph.D. (1970) in zoology from the University of Kansas.

Before coming to Iowa State University, Klaas served as an administrative officer at the U.S. Army Quartermaster School. He got his start in teaching when he was named a teaching assistant (159-1960) at Southern Illinois University. Klaas then served as a field assistant with the University of Kansas State Biological Survey (1960-1962) and with the University of Kansas Museum of Natural History (1962-1963). While pursuing his doctorate, he worked as a graduate assistant (1963-1965) at the University of Kansas. He was named Associate Professor (1965-1971) of biology at Rockhurst College in Kansas City, Missouri, and then Research Biologist (1971-1975) with the Patuxent Wildlife Research Center. Klaas continued to serve as a Wildlife Research Biologist with the U.S. Fish and Wildlife Service and U.S. Geological Survey until his retirement.

Klaas joined the staff at Iowa State as Assistant Leader (1975-1992) of the Iowa Cooperative Wildlife Research Unit and as Associate Professor (1975-1980) in the Department of Animal Ecology. He was later promoted to Professor (1980-1999) and Leader (1992-1999). Klaas retired on December 31, 1999, and was named Professor Emeritus in 2000.

Klaas is an active member of the Ames community and continues to support environmental concerns in his retirement. He is a member of many local, state, and national groups dedicated to environmental protection and preservation, including the American Ornithologists' Union, the Audubon Society, and the National Geographic Society. He served as Commissioner (2000-2008) of the Story County Soil and Water Conservation District and helped organize support for the Ada Hayden Heritage Park in Ames. Klaas has received numerous awards including the Distinguished Iowa Scientist Award (2000) from the Iowa Academy of Science, Professional Award of Merit (2001) from the North Central Section of The Wildlife Society, and Outstanding Volunteer Service Award (2005) from the Natural Resources Conservation Council, United States Department of Agriculture.

He is married to the former Janet Engler of Kansas City, Missouri. They have three children: Zak, Ben, and Abby.