Dr. John D. Wehausen is an applied population ecologist who has studied bighorn sheep populations in California since 1974, beginning with his Ph.D. dissertation work in the Sierra Nevada, where he has continued to work since completing his dissertation. In the Owens Valley region he has carried out intensive studies of bighorn sheep populations in the White and Inyo Mountains in addition to the Sierra Nevada. Since 1984 he has also researched bighorn sheep populations in the eastern Mojave Desert. Dr. Wehausen began as a botanist and plant ecologist and moved into herbivore ecology through an interest in the herbivore-vegetation interface. Consequently, his field studies of bighorn sheep population ecology encompass a wide trophic spectrum from influences of soil parent material and soil moisture on plant communities and plant phenology as they affect bighorn sheep nutrition, to the predators that prey on the sheep and potentially influence their habitat selection. In the early 1990s Dr. Wehausen expanded his research to include cranial morphometric studies relative to taxonomic questions of bighorn sheep. Since the end of the 1990s he has become increasingly engaged in molecular population genetic studies of bighorn sheep and other associated species. His studies have had a strong conservation orientation. Beginning in the 1970s, he has worked closely with various resource management agencies to help establish and carry out data-based conservation programs for bighorn sheep. He was a member of the recovery team for bighorn sheep in the Peninsular Ranges in California and helped draft the recovery plan for that distinct population segment of desert bighorn sheep. Following their listing as a federal endangered species, he wrote most of the recovery plan for bighorn sheep in the Sierra Nevada. Most recently he has drafted for the California Department of Fish and Wildlife a conservation plan for desert bighorn sheep in California outside of the Peninsular Ranges. In 1995 Dr Wehausen helped found the Sierra Nevada Bighorn Sheep Foundation and has served as its president throughout its history. In 2012 Dr. Wehausen retired as an Associate Research Scientist with the University of California’s White Mountain Research Station, but continues to work full time on bighorn sheep conservation issues in California including the Sierra Nevada.