Large mammals shape their environment and are of great importance to the tourism and conservation industry. Research by the Mammal Research Institute (MRI) in the Faculty of Natural and Agricultural Sciences at the University of Pretoria provides invaluable information to help manage both wild and captive populations.

Researchers involved with the MRI produced some exciting research on large mammals over the last year.

Lions are apex predators that experience multiple threats due to human activity and are classified as vulnerable (IUCN Red List). Analysis by Dr Peter Lindsey and co-authors (Bauer et al., 2020) teaches us more about their distribution and numbers. Eleven threats were identified in total, with human-lion conflict and depleted food supply (resulting from the bush meat trade) emerging as the top threats. Lion conservation is a complicated problem, with many threats interacting simultaneously, which can easily result in the complete eradication of a lion population. A problem tree and root-cause analysis was used to visualise this complex situation. According to Dr Lindsey, 'The results of this study will aid conservation managers, social scientists and politicians in teasing apart the underlying issues before lion conservation can be tackled efficiently.'

In zoological terms, vigilance is more than looking out for danger, it is also observing what other animals are doing around you (social vigilance). A study on impala by Anita van Deventer and Prof Adrian Shrader (2021) investigated circumstances under which individuals within a herd prioritise different behaviours. Social vigilance involves watching to see if other animals are alarmed and where they are feeding, for example. If an impala is to survive, it must find the right balance between foraging and avoiding predators. Herd size was predictably greater in areas where predator numbers and density were higher. However, it was surprising that impala in the middle of the herd reduced their antipredator vigilance and increased their social vigilance but didn't increase overall vigilance. In contrast, animals at the edges increased both social and anti-predator vigilance, as well as proportionally increasing their anti-predator vigilance. This demonstrates that centrally positioned impala are advantaged because they have more time to forage or find better forage, in addition to being at reduced risk of predation due to safety in numbers. Interestingly, impala in predator-free areas showed the same amount of vigilance, regardless of herd position, but still exhibited high levels of total vigilance, despite the reduced threat.

In another paper on vigilance, Dr Mark Keith and colleagues (Yiu et al., 2021) looked at predation risk in relation to intense and routine vigilance in Burchell's zebra and blue wildebeest. Both species form an essential part of the lion diet. Extreme vigilance is when the environment is scanned continuously and all other activity stops, while routine vigilance is when the animal continues to chew while looking out for predators. The relationship between these two behaviours was calculated and found to be inversely proportional. Zebra's intense vigilance was lower outside lion home ranges, and their routine vigilance was higher in herds. The intense vigilance of wildebeest decreased with an increase in herd size and increased with the presence of a calf. Wildebeest differed from zebra, showing similar vigilance in and outside lion home ranges, but when grass was tall, intense vigilance increased due to the perceived higher ambush risk. Intense vigilance also increased with a higher tree density but, interestingly, decreased at a certain threshold, probably because wildebeest benefited from added tree cover. Wildebeest relied more on safety in numbers to avoid predation than zebra did.

References
Bauer, H; Dickman, A; Chapron, G; Oriol-Cotterill, A; Nicholson, SK; Sillero-Zubiri, C; Hunter, L; Lindsey, P & Macdonald, DW. 2020. Threat analysis for more effective lion conservation. Oryx: 1–8.

Van Deventer, A & Shrader, AM. 2021. Predation risk and herd position influence the proportional use of antipredator and social vigilance by impala. Animal Behaviour, 172:9–16.

Yiu, SW; Keith, M; Karczmarski, L & Parrini, F. 2021. Predation risk effects on intense and routine vigilance of Burchell's zebra and blue wildebeest. Animal Behaviour, 173:159–68.