Sidney S. Frissell died in Hamilton, MT, on March 13, 2026. He was a Forestry professor and Dean at the University of Montana, woodsman and an avid birder, watercolor painter of birds in their natural habitats, and lifelong Ham radio operator. …Sid earned a Forestry degree at the University of Minnesota and went to work for the US Forest Service in Randall, Washington. Within a year he returned to graduate studies at Minnesota, earning a Master’s degree and then pursuing a PhD. …In collaboration with colleagues he made lasting contributions in wildlife ecology and management, forest recreation, and wilderness management, coauthoring a methodology for assessing sustainability of use of campsites still applied by forest managers today. After serving several years as Associate Dean of the School of Forestry at the University of Montana, he was promoted to Dean in 1986. …He retired at a relatively young age to pursue a second career in wildlife illustration and bird painting…