An animal's diet is an important attribute of its niche, and affects the role that it plays in the ecosystem. Comparing the diets of sympatric species reveals the level of dietary niche overlap between them, which can be used to gauge the potential for competition, as well as each species' vulnerability to competitive exclusion. Because of a morphology adapted to predation, sympatric carnivores can have particularly aggressive and dangerous competitive interactions; the intensity of which may be directly related to the amount of overlap in prey species consumed. Using predator scat analysis and prey survey techniques, we analyze and compare the underlying mechanisms of prey selectionprey body size and group sizebetween sympatric populations of leopard Panthera pardus and lion Panthera leo, to test for possible means of competitive avoidance between them. Because leopard and lion differ in both size and social structure, we controlled for the differing prey handling ability of each species, and found that there was still a significant difference in mean prey body size preference between the two carnivores (P = 0.050), despite a relatively high level of dietary niche overlap (0.717). Both species avoid prey in larger groups, but the tendency is more pronounced for leopards. Where intraguild competitors overlap spatiotemporally, dietary niche segregation such as this may be a mechanism through which competition is avoided and, in the case of carnivores, could reduce the frequency of potentially costly interactions.

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Mammals use endogenously produced heat to maintain a high and relatively constant core body temperature (T b ). How they regulate their T b during reproduction might inform us as to what thermal conditions are necessary for optimal development of offspring. However, few studies have measured T b in free-ranging animals for sufficient periods of time to encounter reproductive events. We measured T b continuously in six free-ranging adult female African lions (Panthera leo) for approximately 1 year. Lions reduced the 24 h amplitude of T b by about 25% during gestation and decreased mean 24 h T b by 1.3 + 0.18C over the course of the gestation, reducing incidences of hyperthermia (T b . 39.58C). The observation of improved homeothermy during reproduction may support the parental care model (PCM) for the evolution of endothermy, which postulates that endothermy arose in birds and mammals as a consequence of more general selection for parental care. According to the PCM, endothermy arose because it enabled parents to better control incubation temperature, leading to rapid growth and development of offspring and thus to fitness benefits for the parents. Whether the precision of T b regulation in pregnant lions, and consequently their reproductive success, will be influenced by changing environmental conditions, particularly hotter and drier periods associated with climate change, remains to be determined.

Previous research has shown that African lions (Panthera leo) have the ability to discriminate between conspecific vocalisations, but little is known about how individual identity is conveyed in the spectral structure of roars. Using acoustic -accelerometer biologgers that allow vocalisations to be reliably associated with individual identity, we test for vocal individuality in the fundamental frequency (f0) of roars from 5 male lions, firstly by comparing simple f0 summary features and secondly by modelling the temporal pattern of the f0 contour. We then assess the application of this method for discriminating between individuals using passive acoustic monitoring. Results indicate that f0 summary features only allow for vocal discrimination with 70.7% accuracy. By comparison, vocal discrimination can be achieved with an accuracy of 91.5% based on individual differences in the temporal pattern of the f0 sequence. We further demonstrate that passively recorded lion roars can be localised and differentiated with similar accuracy. The existence of individually unique f0 contours in lion roars and their relatively lower attenuation indicates a likely mechanism enabling individual lions to identify conspecifics over long distances. These differences can be exploited by researchers to track individuals across the landscape and thereby supplement conventional lion monitoring approaches.