Abstract: Surveying snow leopard prey species such as argali, ibex or blue sheep through traditional ground-based observations is time-consuming, expensive, and challenging. Aerial drones present a promising alternative. We tested using thermal-sensor- equipped drones to count ungulate populations in Mongolia’s Ikh Nart Nature Reserve, surveying ~400km of transects along five fixed routes for forty-three missions. Drones detected 235 prey animals and 209 livestock; 26% of all sightings were in areas that would not have been visible to hypothetical ground-based observers. Our tests reinforced the utility of drones for counting snow leopard prey and highlighted important issues and future advances for supporting largely autonomous prey surveys. We recommend biologists build upon existing technology to attain an inexpensive, easy to use, and field ready set of equipment and procedures that can reliably improve or replace traditional transect or point count methods for large prey species.