Migratory species provide important benefits to society, but their cross-border conservation poses serious challenges. By quantifying the economic value of ecosystem services (ES) provided across a species’ range and ecological data on a species’ habitat dependence, we estimate spatial subsidies–how different regions support ES provided by a species across its range. We illustrate this method for migratory Northern Pintail ducks in North America. Pintails support over $101 million annually in recreational hunting and viewing and subsistence hunting in the U.S. and Canada. Pintail breeding regions provide nearly $30 million in subsidies to wintering regions, with the “Prairie Pothole” region supplying over $24 million in annual benefits to other regions. This information can be used to inform conservation funding allocation among migratory regions and nations on which the pintail depends. We thus illustrate a transferrable method to quantify migratory species-derived ES and provide information to aid in their transboundary conservation.