This research analyzes the roles of action ethnobiology and public anthropology in “ecological distribution conflicts”—disputes over the benefits and burdens of natural resources—in policy-oriented research and advocacy. It considers the Natural Resources Defense Council's (NRDC) international campaigns to protect “frontier landscapes” of the Western hemisphere. Specifically, I examine case studies in Chilean Patagonia and the boreal forest region in the Canadian Northeast. Despite geographical, historical, and cultural differences, NRDC's campaigns in these two regions involved a shared focus on developing advocacy strategies that draw on biocultural knowledge to advance stronger environmental protections. NRDC and its local partners used ethnoecology as an environmental tactic to protect rivers from proposed large hydroelectric dam projects in Chile, and drew upon ethnozoology to preserve caribou threatened by industrial logging in Canada. To consider the synergies and tensions of environmental advocacy and Indigenous sovereignty in these two instances, I analyze partnerships between environmental activists, lawyers, and scientists on the one hand, and Indigenous leaders and local residents on the other. Taking a public anthropological approach, this comparative research sheds light on the role of action ethnobiology as a condition of possibility for advocacy to enhance environmental sustainability and Indigenous sovereignty across the Americas.