Monitoring river dolphins in the Amazon is expensive and time consuming. Because of that there is a scarce understanding about their abundance and distribution. Our study aimed at evaluating the effectiveness of UAV to optimize data collection in population studies of river dolphins. We tested the potential for detection and accuracy of dolphin images captured using a drone in real conditions. Two quadcopter drones (DJI Phantom 3 and 4) were launched from a double-decker riverboat navigating at 10 km/h, in an average distance of 50 m parallel to the river margin. 80 km of transects were sampled by drones, totalling eight hours of videos recorded. River dolphins were clearly detected in a range of 100m from the drone, being possible to distinguish animals from the two species. However, strong winds made it hard to land the drones. Preliminary results have shown this technology has great potential to support population studies on river dolphins. However, this method requires improvements on the range of detection, flight duration, and development of an algorithm to provide animals automated detection. Insight are welcome!