The Amazon River dolphin Inia geoffrensis occurs throughout the basins of the Amazon and Orinoco Rivers and is categorized as Endangered on the IUCN Red List. Using satellite tracking data from eight dolphins (one female and seven males) in the Peruvian Amazon, we demonstrate that these dolphins inhabit a variety of habitat types and have core areas and home range areas of variable magnitudes. To gain a better understanding of how threats affect these dolphins, we examined the distance of dolphin records to locations of current and potential future anthropogenic threats. On average, dolphin home ranges overlapped with fisheries by 89%. Dolphins were found at an average distance of 252 km from the nearest proposed dam and 125 km from the nearest proposed dredging site. Given that many of these threats are still in the planning stage, we advise the government to consider the negative effects these activities have already had on other riverine species before proceeding. Additionally, efforts should be made to expand river dolphin tracking programmes to span multiple seasons, to track more females at our study sites and to increase the numbers tracked overall in other areas to improve our knowledge of the species' movement patterns.

Quantifying the abundance of species is essential for their management and conservation. Much effort has been invested in surveys of freshwater dolphins in the Amazon basin but river dimensions and complex logistics limit replication of such studies across the region. We evaluated the effectiveness of using unmanned aerial vehicles (UAVs) for surveying two Amazon dolphin species, the tucuxi Sotalia fluviatilis and pink river dolphin Inia geoffrensis, in tropical rivers. In 2016 we conducted drone and visual surveys over 80 km of the Juruá River in Brazil. The aerial surveys provided higher accuracy than human observers in counting individuals detected in groups. Compared to estimates derived from visual surveys, the use of UAVs could provide a more feasible, economical and accurate estimate of Amazon river dolphin populations. The method could potentially be replicated in other important areas for the conservation of these species, to generate an improved index of river dolphin populations in the Amazon.