The ecology, behaviour, and ecosystem engineering of hippopotamus (Hippopotamus amphibious) in northern Botswana
Despite their Vulnerable status and importance to the ecosystem, hippos are extremely understudied. My project is looking at the ecology, behaviour, and ecosystem engineering of hippos within northern Botswana, the first dedicated study on the species within Botswana. Hippos have long been lauded as a keystone species in swamplands given their role in creating extensive trails in reed beds during their daily commute from their diurnal resting grounds in water to their nocturnal grazing areas. However, the mechanism of this trail creation, and their impact of the trails on the ecosystem has never been studied. Using drone technology, camera traps and observational studies, I research how hippos utilise and impact on the environment.
By regularly flying a drone over my study area and taking overlapping photos, I produce high resolution maps which I use to identify hippo trails and track changes to their width, length and extent of vegetation encroachment. I then relate these changes to the use of the paths by the hippos, through camera traps and by mapping hippo numbers (using the drone) within the pools that the trails extend from. Over 18 months, this process will be continued to understand how often new trails are being created, which hippos are creating the trails, and how quickly the reeds reclaim the paths when they’re not being used.
In addition, by mapping the area and the hippo distribution, I look at how hippos are selecting their habitats, and how this changes with environmental pressures. Already I have seen significant changes to the hippo distribution within the area with changing seasons and a reduction in surface water; the hippos have recently retreated to just two large lagoons, as opposed to the seven they used to occupy. Understanding these changes will let us understand how and potentially why hippos occur where they do, but also how long term changes to the environment might impact their populations.
I am also conducting observational studies in order to complement the above methods, in understanding how and where hippos spend their day. Whilst logistically and physically difficult, I am conducting these studies not only during the day, but also at night. Nocturnal behaviour on hippos has never been recorded despite this being the time when they are most active.
Based in Botswana until 2019