J.N.T. Kushata, S. Périquet, T. Tarakini, M. Muzamba, B. Mafuwa, A.J. Loveridge, D.W. Macdonald, H. Fritz, M. Valeix; Journal of Zoology, vol 304, pp. 132-140
It is a well-known fact that spotted hyaenas (Crocuta crocuta) are nocturnal animals. Therefore, after focussing on their ecology and behaviour at night in Hwange National Park, Zimbabwe, members of the CNRS Hwange LTSER (Long-Term Socio-Ecological Research site) realised that one aspect of this species’ ecology was clearly under-studied. The question raised was: ‘Where and why do hyaenas choose certain areas for resting during the day?’. We thus centered our interest on trying to answer what influenced hyaena diurnal rest site selection focusing on habitat type, distance to waterhole and the risk of encountering lions (Panthera leo), their main predators/competitors in Hwange.
We answered the ‘where’ part of the question with data collected thanks to GPS collars deployed on hyaenas during Stéphanie Périquet’s PhD. Collaring spotted hyaenas is quite a challenge, even at carcasses, particularly because once darted, hyaenas do not stay put, they just run in a frenzy into the dense bush and keeping track of the darted individual is a mission! However, after months of efforts, we managed to collar seven hyaenas in three different clans.
The collars deployed provided us with hourly locations at night for about 1.5 years. They were also set to record GPS locations three times during the day and we chose the midday location as the actual rest site location. After downloading the data, rest sites were investigated on foot to determine the microhabitat (habitat type and visibility distance). Walking in Hwange was not the easiest thing to do due to the dense bushy vegetation and the presence of dangerous animals such as elephants (Loxondonta Africana), buffalos (Syncerus caffer) and of course, lions. We therefore had to be accompanied by an armed park ranger on every single excursion. Because of this, we had to restrict our rest site investigation to those located within 2 km from a road.
Then we needed to understand factors affecting hyaenas’ choice for a rest site. Obviously, vegetation and shade availability sprang into our minds. We devised protocols for estimating visibility distance (reflecting vegetation density) and shade at the rest site. Because of the remote location of our field station and the rest sites, and the challenging economic times that Zimbabwe was facing, we had limited access to resources to build equipment. We resorted to our imagination to make up a board (from readily available white curtains) that an observer would walk with. Because the shade availability would be changing through the course of the day, we decided to use the canopy cover as a proxy of shade availability at the rest site. An observer thus had to walk looking up at branches and bushes to estimate cover at 40 locations around the rest site. All this while being careful not to fall into holes or step on snakes!
Even though hyaenas are usually not hunting or foraging during the day, our thinking led us to test the effect of prey availability around rest sites. Surely, hyaenas would try to rest close to prey hotspot so that they don’t have to travel too much between meals, but not so close that the prey would detect them and run away. Such prey hotspots are located around waterholes in Hwange. So naturally, we incorporated the distance to the closest waterhole as a factor potentially affecting rest site selection. It turned out that we were wrong. Proximity to a waterhole was not a factor influencing rest site location and hyaenas seem to rest at random distances from water.
Then came the realisation that proximity to roads might also affect the options of hyaenas’ resting sites. Roads could have two opposite effects. The first one is disturbance by vehicles. However, traffic is very limited in Hwange, and during the period when the study was conducted, tourism activities were very infrequent. The second effect of roads is creating paths of least resistance for hyaenas (and other animals) to travel from one waterhole to the next. Based on this, we expected hyaenas to rest relatively close to roads, which our analyses confirmed.
And last but not least, we were also interested in the effect of the presence of lions on hyaenas’ rest site use. Not only are lions spotted hyaenas’ main competitors, but they are also potential predators. It would therefore make sense for hyaenas to rest in places where they have low probability of encountering lions. Even though both species rest during the day, it would be safer for hyaenas to rest in places far away from lions so that when both species start being active again in the late afternoon/early evening, they don’t encounter each other. Thanks to GPS collars fitted on lions (in both coalitions and prides) in the study area by the Hwange Lion Research Project of WildCRU (Oxford University), we were able to derive long and short-term risks of encountering lions. We found that hyaenas did not avoid resting places located in the core of lion home ranges. This suggests that hyaenas do not base the rest site choices on predictive knowledge of where they have higher probability of encountering lions. However, we found that most of the rest sites used were located more than 5 km away from any early morning lion location on the same day. In addition, when lions had been close by in the early morning, hyaenas tended to rest in denser vegetation. These findings therefore suggest that hyaenas respond to the recent presence of lions instead of the long-term knowledge of their whereabouts. Overall, these results shed new light on the mechanisms of coexistence between large predators.
By spending time walking in the bush, we got to see nature in a different light. We witnessed several lion kills, and spotted coalitions of cheetahs and mating snakes among other sightings. The best and greatest of all however, was seeing a female hyaena in broad daylight and its inquisitive cubs peeping from their den under collapsed drainage tunnels.