With hunting and habitat loss driving wild hippo populations further into decline, keeping track of the semi-aquatic African mammals' numbers is now a critical focus for conservation efforts.
Observing the species from land can prove difficult and extremely dangerous. As well as being hard to spot in the water, Hippopotamus amphibious are very territorial and often do not take kindly to unwanted visitors.
That's why researchers from UNSW decided to take a different approach when it comes to tracking Africa's most deadly mammal.
They measured hippo populations in Botswana's Okavango Delta region for seven days with drone surveillance technology in a collaboration with Elephants Without Borders.
"Even though hippos are a charismatic megafauna, they are surprisingly understudied, because of how difficult it is to work with nocturnal, amphibious and aggressive animals," Victoria Inman, lead author and PhD candidate at the UNSW, said on Tuesday.
"(But) our study shows that small, commercially available drones are a simple, affordable and effective method for wildlife conservation organizations to monitor threatened species."
"Long-term statistics on animal populations are critical for understanding the nature and extent of species' declines."
"Drone data could be routinely collected in different river systems, providing a guide to the numbers in hippo pods, seasonal changes and the ability to track the long-term status of hippo populations."
Seeing the use of drones as an increasingly valuable tool for observing wildlife populations, co-author of the study and Director of the Centre for Ecosystem Science at UNSW Professor Richard Kingsford said the bird's eye view also allowed the team to determine the age of individual hippos based on their body lengths.
"This method will be important for monitoring the age structure of hippo populations in different parts of Africa and to track breeding," he said.
"Importantly, our surveys also effectively tracked changes in the hippo pod over time, as adults emigrated from the lagoon as it dried - a typical response of hippos to changing water availability."
"Drones also provide a viable alternative to land-based counts and have low impact on hippos, offering further opportunities to survey inaccessible areas and, just as critically, collect this information safely," he said.