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Shifting prey selection has been identified as a mechanism potentially regulating predator-prey interactions, but it may also lead to different outcomes, especially in more complex systems with multiple prey species available. We assessed changing prey selection by lions, the major predator for 12 large herbivore species in South Africa's Kruger National Park. The database was provided by records of found carcasses ascribed to kills by lions assembled over 70 years, coupled with counts of changing prey abundance extending over 30 years. Wildebeest and zebra constituted the most favored prey species during the early portion of the study period, while selection for buffalo rose in the south of the park after a severe drought increased their vulnerability. Rainfall had a negative influence on the proportional representation of buffalo in lion kills, but wildebeest and zebra appeared less susceptible to being killed under conditions of low rainfall. Selection by lions for alternative prey species, including giraffe, kudu, waterbuck, and warthog, was influenced by the changing relative abundance and vulnerability of the three principal prey species. Simultaneous declines in the abundance of rarer antelope species were associated with a sharp increase in selection for these species at a time when all three principal prey species were less available. Hence shifting prey selection by lions affected the dynamics of herbivore populations in different ways: promoting contrasting responses by principal prey species to rainfall variation, while apparently being the main cause of sharp declines by alternative prey species under certain conditions. Accordingly, adaptive responses by predators, to both the changing relative abundance of the principal prey species, and other conditions affecting the relative vulnerability of various species, should be taken into account to understand the interactive dynamics of multispecies predator-prey webs.

Spatial patterns of and competition for resources by territorial carnivores are typically explained by two hypotheses: 1) the territorial defence hypothesis and 2) the searching efficiency hypothesis.According to the territorial defence hypothesis, when food resources are abundant, carnivore densities will be high and home ranges small. In addition, carnivores can maximise their necessary energy intake with minimal territorial defence. At medium resource levels, larger ranges will be needed, and it will become more economically beneficial to defend resources against a lower density of competitors. At low resource levels, carnivore densities will be low and home ranges large, but resources will be too scarce to make it beneficial to defend such large territories. Thus, home range overlap will be minimal at intermediate carnivore densities.According to the searching efficiency hypothesis, there is a cost to knowing a home range. Larger areas are harder to learn and easier to forget, so carnivores constantly need to keep their cognitive map updated by regularly revisiting parts of their home ranges. Consequently, when resources are scarce, carnivores require larger home ranges to acquire sufficient food. These larger home ranges lead to more overlap among individuals' ranges, so that overlap in home ranges is largest when food availability is the lowest. Since conspecific density is low when food availability is low, this hypothesis predicts that overlap is largest when densities are the lowest.We measured home range overlap and used a novel method to compare intraspecific home range overlaps for lions Panthera leo (n = 149) and leopards Panthera pardus (n = 111) in Africa. We estimated home range sizes from telemetry location data and gathered carnivore density data from the literature.Our results did not support the territorial defence hypothesis for either species. Lion prides increased their home range overlap at conspecific lower densities whereas leopards did not. Lion pride changes in overlap were primarily due to increases in group size at lower densities. By contrast, the unique dispersal strategies of leopards led to reduced overlap at lower densities. However, when human‐caused mortality was higher, leopards increased their home range overlap. Although lions and leopards are territorial, their territorial behaviour was less important than the acquisition of food in determining their space use. Such information is crucial for the future conservation of these two iconic African carnivores. [ABSTRACT FROM AUTHOR]

Movement patterns of lions (Panthera leo) reveal how they hunt large herbivores in heterogeneous landscapes such as the Kruger National Park in South Africa. Large herbivores are distributed differently on the landscape and therefore have different vulnerabilities as prey for lions. For instance, blue wildebeest (Connochaetes taurinus) occupy small grazing lawns at night but are difficult for lions to capture because open areas lack cover for stalking. African buffalo (Syncerus caffer) aggregate in large herds but are less available because these herds only intermittently enter the home ranges of individual lion prides. Unlike large herds of wildebeest and buffalo, plains zebra (Equus quagga) move widely in small herds while browsing greater kudus (Tragelaphus strepsiceros) and giraffes (Giraffa camelopardalis giraffa) generally occur in lower densities. We used spatial data derived from GPS collars to investigate several hypotheses regarding the movements of three lion prides in response to their prey. We found that lions were most active and moved longer distances during nighttime than during daytime. Lions remained within their core home ranges on 87% of nights and wandered to the outlying areas of the home ranges every second night. Lions visited grazing lawns, that is, area of short grass, where wildebeest herds resided every second night, and moved toward the direction of buffalo herds within 2 km of vicinity. Lions spent more time near riverbanks that provided dense woody cover at night than expected but concentrated only weakly near sites with surface water where herbivores drank in the dry season. Our study contributes to understanding how lions vary their movements in response to the spatial and temporal heterogeneity in the relative availability and vulnerability of multiple prey species. [ABSTRACT FROM AUTHOR]

Prey mortality depends on the likelihood of encountering a predator and of being killed following such an encounter. While the proactive responses of large herbivores to the risk of predation have been well documented, the reactive responses of prey following encounters have been less well studied and restricted mostly to northern temperate ecosystems. We postulated that the reactive response should depend on the habitat selection of the prey species as well as the hunting tactic (cursorial versus stalking) of the predator. We investigated the reactive responses of a selective grazer, the blue wildebeest, Connochaetes taurinus , and a generalist grazer, the plains zebra, Equus quagga , to encounters with lions, Panthera leo , their main predator, in Kruger National Park. We used simultaneous global positioning system (GPS) locations of prey and predators to identify encounters and assess their frequency and characteristics (e.g. time of day). We compared both the immediate response (stay or flee) and subsequent movement (remain in the habitat patch or relocate) of the two ungulate species following encounters with lions. Despite being more predictably located in open short grass areas, wildebeest encountered lions no more frequently than zebra. However, being more selective for these particular habitat types, wildebeest more often stayed near the encounter site than zebra. Specifically, wildebeest were less likely to leave when located in more open areas with short grass providing both high-quality food and little concealment for stalking lions. We suggest that this is because wildebeest incur higher risks and greater feeding costs than zebra should they relocate, owing to their narrower preference for areas of short grass. Our findings show how the adaptive responses of wildebeest and zebra following encounters with their major predator depend on their habitat requirements. [ABSTRACT FROM AUTHOR]

Dispersal is a risky process, both through social pressures and the uncertainty in finding resources. The white rhinoceros is unusual among rhinoceros species in its incipient sociality, manifested through the formation of temporary or more persistent groups involving subadults of both sexes plus adult females without small calves. We describe the probing excursions made by subadult white rhinos out of their established home ranges which were invariably made with a companion. We suggest additional benefits of companionship in such dispersal movements, besides diluting predation risk, via (1) reducing the likelihood of being attacked by territorial males and (2) familiarization with a wider region of the environment, guided by the companion. This "buddy system" may be important in reducing the high costs potentially associated with dispersal. [ABSTRACT FROM AUTHOR]