Saving endangered species is a high priority, especially when they are charismatic icons for conservation and provide important ecosystem services. The Grevy’s zebra is a perfect example of both as zebra movements provide an early warning system to pastoralist herders that rangelands are heading to deterioration. While basic research has identified the ecological reasons for the species’ rapid decline, human attitudes and policies have been slow to evolve, in part because the actual population numbers are suspect. Our multi-disciplinary research collaboration of biologists and computer scientists is armed with new algorithms for identifying individual zebras from photos, but given that Grevy’s zebras roam over 25,000 km2 of difficult terrain, the only sure-fire way of gathering sufficient data was to create a large-scale citizen science event: the Great Grevy’s Rally. For two days, over 350 members of the public drove tracks within 45 counting blocks and took over 40,000 pictures. From these images, computer algorithms estimated the national population at 2350 zebras and showed which counties were gaining or losing zebras. The images revealed demographically sustainable populations with 30% recruits. Without the joint power of scientists and citizen scientists working with advanced computer technology, none of this would have been possible. We present the lessons learned from our multi-disciplinary combination of advanced technology and citizen science to tackle a short but intensive wildlife study.