Mating patterns of dusky dolphins (Lagenorhynchus obscurus) explored using an unmanned aerial vehicle

Few studies have explored the mating patterns of populations of cetaceans, largely because of logistical challenges. We used an Unmanned Aerial Vehicle to follow and video-record 25 groups of mating dusky dolphins (Lagenorhynchus obscurus) near the surface of the water and to explore the possibility of varying behavioral patterns exhibited in disparate mating contexts. We collected aerial footage of dolphins in traditional isolated mating pods (IP) and of dolphins mating within larger pods (BP) and compared differences in group size, swimming speed, bearing change, percent time at the surface of the water, female respiration rate, copulatory position, and sex-specific mating behaviors. Only mean group size and some sex-specific mating behaviors varied significantly between the two mating contexts. Group sizes were larger in IP than BP. Males engaged in more interference behaviors in IP compared to BP than expected by chance. Females performed fewer speed bursts but more rolls on their backs in BP compared to IP than expected by chance. Several similarities and differences were found in comparison to boat-based follows of the same population of dolphins. We highlight the value of UAVs for non-invasive and accurate collection of cetacean behavioral data.