Featured photo: Researcher Keenan Stears and Veterinarian Dr. Epaphras Muse attach a GPS collar to the ankle of a safely immobilized hippo.
Lack of knowledge about hippopotamus ecology has limited efforts to manage this iconic African species, but research funded by Safari Club International Foundation is increasing our understanding of hippo ecology and management. A recent study conducted in Ruaha National Park in Tanzania involved GPS tracking 10 male hippos to get a better understanding of their habitat selection and landscape-level movement patterns throughout the course of a year. The peer-reviewed article, authored by Keenan Stears, from the University of California Santa Barbara, and coworkers was recently published in Scientific Reports and the results could play a key role in shaping hippo conservation strategies across Africa moving forward.
Hippos are important ecosystem engineers across African savannas, but unfortunately their populations are declining due to a combination of habitat loss and degradation and poaching. Since hippos rely heavily on a suitable water supply, they are particularly vulnerable to human-driven hydrological changes within their environments. Increased water extraction associated with agriculture and human development across the hippo’s native range is causing lakes and rivers to dry up. Climate associated shifts in rainfall, like prolonged droughts and intensified rainfall events, are exacerbating those issues and potentially increasing stress on hippo populations. These factors are increasingly displacing hippos, forcing them to disperse to lower quality pools of water and increasing intraspecific conflict, particularly among adult males.
The recent SCIF-supported research is the first to apply GPS tracking technology to obtain long-term information about hippo movements. The researchers focused on male hippos because they are likely to be more affected by changes in water availability. Competition and aggressive interactions increase as water availability declines. The results indicated that changes in water availability influenced the movements of large sub-adult males the most. During the dry season, when water was most limited, large sub-adult males exhibited large upstream movement (up to 15 km) to where water was more available. These movements were highly erratic, which indicates that these males were constantly interacting with dominant males while trying to find suitable river pools. These potentially lethal aggressive interactions forced these dispersing large sub-adult males to continue to move further upstream. During the wet season, when suitable river pools were abundant, large sub-adult males moved downstream to where hippo densities were lower to try and establish their own territories.
In contrast, the movements and home ranges of dominant and small sub-adult males (males that have not reached sexual maturity and are therefore tolerated by dominant males) were less impacted by water availability. These individuals remained in the same river pools throughout the year. Assessing the movement patterns of the hippos also helped researchers further identify the type of habitat buffers needed around water bodies to support foraging areas that hippos rely on to meet their dietary needs. The significant movement displayed by large sub-adult male hippos during the dry season coupled with stress from overcrowding in limited pools of water may have deleterious effects on hippo populations in increasingly water-stressed environments. More importantly, the research also provides insight into how hippo populations can be most effectively conserved through water management policies like ensuring minimum environment flow requirements, protecting flood plains, anticipating movements and ensuring habitat connectivity, and extending buffer zones to include ample foraging areas while reducing human-hippo conflicts.
Safari Club International Foundation is committed to using dollars generated by hunters to support the conservation of important species by ensuring that the best available science is used in wildlife policy and management, and to demonstrating the constructive role that hunting plays in the conservation of biodiversity worldwide.
