Spotted hyaena survival and density in a lion depleted ecosystem: The effects of prey availability, humans and competition between large carnivores in African savannahs

Abstract

Interspecific competition between large carnivores is not well understood due to the complexity of carnivore guild dynamics and the array of ecological and human factors affecting them. The loss of a carnivore guild's dominant species can therefore provide considerable insights. We evaluated spotted hyaena density and demography from Zambia's Liuwa Plain National Park, a recovering ecosystem where the hyaena's main competitor, the African lion, was severely reduced to 3-5 animals. Using data from 233 individuals in five clans and mark-resight robust design models we estimated population size, density, age and sex-specific annual survival rates for the hyaena population from 2010-2013 and tested for the effect of human settlements, prey density, competition with lions and hyaena clan size on mean hyaena survival. We estimated a minimum density of 0.13 hyaenas/km 2 and maximum density of 0.52 hyaenas/km 2. Density fluctuated with seasonal migrations of the main prey species, the blue wildebeest. Mean annual survival across all age classes was 0.93 (95%CI: 0.39-0.99). With high survival rates across all sex and age classes, we found no detectable effects of ecological or anthropogenic factors on survival. These results suggest that the combination of abundant prey, weak human-carnivore conflict, and weak competition from lions provide very favourable conditions for hyaena survival. Additional investigations of hyaena demography concurrent with lion population recovery efforts can provide considerable insights into the dynamics of carnivore competition and predation in African savannahs and the human and ecological factors affecting them.

The relationship between direct predation and antipredator responses: a test with multiple predators and multiple prey

“…Spotted hyenas greatly outnumbered other carnivores within the study area, with 151 known hyenas in four clans, six lions in one pride, 22 wild dogs in two packs, and 17 cheetahs during the period of study (M'soka et al. ). To facilitate observation, we radio collared two or more individuals in each of the hyena, lion, and wild dog groups on the study site, and seven of the cheetahs (Droge et al.…”

“…) and consequently were affected little by the spatial and temporal variation in vegetation structure that complicates inference in many ecosystems (M'soka et al. , Droge et al. ).…”

Spatial and temporal avoidance of risk within a large carnivore guild

“…Other species that were occasionally killed occurred at much lower densities, including common duiker (Sylvicapra grimmia), red lechwe (Kobus leche), steenbok (Raphicerus campestris), common reedbuck (Redunca arundinum), and scrub hare (Lepus saxatilis). Hyenas greatly outnumbered other carnivores within the study area, with populations of 151 hyenas in four clans (M'Soka, Creel, Becker, & Droge, 2016), six lions in one pride, 22 wild dogs in two packs, and 17 known cheetahs. December 2015 for up to 7 days.…”

“…Because the ecosystem we studied is highly uniform with respect to habitat ( Figure 2) and supports a simple ungulate guild dominated by only three species (M'Soka, 2015), the interpretation of spatial and temporal overlaps is simplified considerably.…”

Foraging investment in a long‐lived herbivore and vulnerability to coursing and stalking predators

“…Migratory zebra ( Equus quagga ) are the next most abundant prey species (<8.1 individuals/km 2 ) followed by oribi ( Ourebia ourebi ), tsessebe ( Damaliscus lunatus ), and lechwe ( Kobus leche ). Spotted hyena ( Crocuta crocuta ) are overwhelmingly the most abundant large carnivore persisting in >5 major clans of ~233 hyenas during this study (M'soka, Creel, Becker, & Droge, ). Only two wild dogs ( Lycaon pictus ) packs were known to persist, ranging from 7 to 22 dogs, and 17 cheetah (Acinonyx jubatus ) were individually identified during the course of the study.…”