During his career, Charles Harper illustrated numerous books, notably The Golden Book of Biology, magazines such as Ford Times, as well as many prints, posters, and other works. As his subjects are namely natural, with birds prominently features, Charley often created works for many nature-based organizations, among them the National Park Service; Cincinnati Zoo; Cincinnati Nature Center; Hamilton County (Ohio) Park District; and Hawk Mountain Sanctuary in Pennsylvania. He also designed interpretive displays for Everglades National Park.

Charley Harper passed away on Sunday, June 10th, 2007 after contending with pneumonia for some months.

I guess it comes from an impulse to be honest about everything instead of glorifiying it or making it pretty, or making it expressed in human terms.
— An Illustrated Life