Areas of Expertise: Population biology, landscape connectivity, restoration ecology, community engagement, wolverines and bison.

Stefan oversees Defenders of Wildlife’s Field Conservation programs. He has over 20 years of experience running conservation projects in North America, Asia and Africa. Prior to joining Defenders in 2026, Stefan served as the Director of Colorado Field Conservation for Denver Zoo Conservation Alliance where he advanced bison restoration, bipartisan legislation authorizing wolverine reintroduction to Colorado, state funding for wildlife crossings, bighorn sheep conservation on Navajo Nation, community science on American pika, reintroductions of dung beetles and a multi-department effort to conserve state endangered boreal toads. He served as a Wildlife Biologist with U.S. Geological Survey from 2016-2019, where he led nationwide aerial surveys and developed population models for BLM’s Wild Horse & Burro Program. His Ph.D. focused on argali – the world’s largest wild sheep – in Mongolia’s Gobi Desert, specifically evaluating efforts to promote co-existence with semi-nomadic pastoralists. Drawn by perpetual curiosity to explore landscapes, cultures and species, Stefan has also worked on a diverse array of topics that spans bison population genetics, public health and forest conservation in southern India, Grant’s gazelle hormone physiology and parasitism in central Kenya, blue monkey behavioral ecology in a Kenyan rainforest, savannah elephant demographics in South Africa, white-tailed jackrabbits in Wyoming’s sagebrush sea and urban small mammals in New York City. In a volunteer capacity Stefan is an Adjoint Assistant Professor at University of Colorado Denver, and the Vice Chair of the Board for Summit County Safe Passages.

Stefan holds a Ph.D. in Fish and Wildlife Biology from University of Montana, a M.Sc. in Organismal Biology & Ecology from University of Montana, a M.A. in Conservation Biology from Columbia University, and a B.A. in Government from Dartmouth College.