Mark Nelson is a retired biologist. During his work years, he was kept busy monitoring various environmental impacts using aquatic invertebrates. He also spent a fair amount of time devising schemes for the use of butterfly assemblages in ranking the quality of riparian zones. The past couple of years he’s been planning and taking backpacking trips and finishing up some papers from his past career. Along with Marc Epstein, he coordinates and conducts surveys for the Roxborough State Park (Colorado) Butterfly Project.