No abstract

Life-history patterns in lions Panthera leo living in savanna woodlands of the Kruger National Park, South Africa, were investigated and compared with those of the Tanzanian 'plains-like' ecosystems (e.g. Serengeti Plains and Ngorongoro Crater). First, lower levels of mortality in the juvenile age classes were found in Kruger lions, which in turn, extend the inter-birth period. A further difference was a prolonged period of association of sub-adult males with their natal pride, either directly or in a land tenure system that has not been described previously. Most (80%) of young male coalitions rather than becoming nomadic, remained close to their natal territory after leaving the pride, either as non-territorial sub-adults or adults and even as territorial adults. Only 20% of coalitions did not stay close to their natal range, one of which acquired a territory 20 km away from its natal pride. The pattern of territory acquisition, in fact, was one in which the majority of holders acquired territories close to their natal ranges. These behaviour patterns contrast markedly with those from 'plains-like' ecosystems where dispersing males usually move far away from their natal pride's range (>200) km and often remain nomadic for extended periods of time. Dense bush and access to sufficient prey resources in the form of resident buffalo Syncerus caffer herds may be important factors allowing extended residence near the natal pride's territory. Buffalo were more available in our study area habitat than in neighbouring habitats, and comprised the majority of male lion kills. Extended male residence contrasts markedly with current theory on dispersal in polygynous mammals, which holds that only one sex (females for lions) gain an advantage by staying close to the territory of their natal pride. In Kruger it seems that both sexes gain an advantage by not dispersing far, and use currently undocumented mechanisms to avoid inbreeding.

In many social species, relationships within groups seem to be non-random but related to variables such as rank, kinship or sexual attractiveness. The endangered African wild dog Lycaon pictus is a social carnivore that lives in large, stable packs, and intra-pack associations might be expected to display similar patterns. We investigated patterns of coalition formation (support during dominance interactions, and partnership interactions) and resting associations between members of a captive pack of 19 wild dogs. The social organization of the captive pack was similar to that of free-ranging packs in many respects. Polyadic (group) incidents of coalition support were also observed in a free-ranging pack. Patterns of coalition formation in the captive pack were related to rank. Most aggressive interactions involved high-ranking individuals (particularly the alpha, beta and third-ranking males) and coalitionary support tended to reinforce the existing hierarchy. However, there was at least one example of support influencing a successful rank challenge. Support was affected by potential risks and benefits, the latter including dominance through association and revolutionary alliances. An even stronger pattern overlaid associations between pack members: coalitions and resting associations were strongest between members of the same age-sex cohort, and may have enabled the eventual dominance of younger pack members over adults. Among adults, coalitionary associations were sometimes overridden by intersexual relationships. The results from this captive pack suggest that wild dogs are sensitive to differences in competitive ability. This information, in conjunction with strong affiliative bonds between littermates, is used to manoeuvre for position in the social hierarchy. It may also be important during dispersal, in encounters with other dispersing groups of the same sex. Although most features of the social structure of the captive pack were comparable to those of free-ranging packs, aspects such as the influence of relatedness on coalition formation still need to be explored.

No abstract

The diet and foraging behaviour of 15 radio-tagged pangolins were studied in the Sabi Sand Wildtuin for 14 months, together with the community composition and occurrence of epigaeic ants and termites. Fifty-®ve ant and termite species of 25 genera were trapped in pitfalls of which Pheidole sp. 2 was the most common (27% occurrence). Five termite and 15 ant species were preyed on by pangolins. Six of these species constituted 97% of the diet while ants formed 96% of the diet. Anoplolepis custodiens constituted the major component of the pangolins' diet (77% occurrence) while forming only 5% of the trapped ants. Above-ground ant and termite activity was higher during summer than during winter (an 11-fold difference for A. custodiens), and the above-ground activity was also higher during the day than at night. Pangolins fed for 16% of their foraging time. However, 99% of the observed feeding bouts (mean duration 40 s) were on subterranean prey. The mean dig depth was 3.8 cm. Prey from deeper digs were fed upon for longer periods. A model taking into account various ant characteristics suggests that ant abundance and ant size are the two most important factors determining the number of feeding bouts that pangolins undertake on a particular ant species. Temperature effects on ant activity and their nest characteristics may exclude pangolins from parts of southern Africa.

The diet and foraging behaviour of 15 radio-tagged pangolins were studied in the Sabi Sand Wildtuin for 14 months, together with the community composition and occurrence of epigaeic ants and termites. Fifty®ve ant and termite species of 25 genera were trapped in pitfalls of which Pheidole sp. 2 was the most common (27% occurrence). Five termite and 15 ant species were preyed on by pangolins. Six of these species constituted 97% of the diet while ants formed 96% of the diet. Anoplolepis custodiens constituted the major component of the pangolins' diet (77% occurrence) while forming only 5% of the trapped ants. Above-ground ant and termite activity was higher during summer than during winter (an 11-fold difference for A. custodiens), and the above-ground activity was also higher during the day than at night. Pangolins fed for 16% of their foraging time. However, 99% of the observed feeding bouts (mean duration 40 s) were on subterranean prey. The mean dig depth was 3.8 cm. Prey from deeper digs were fed upon for longer periods. A model taking into account various ant characteristics suggests that ant abundance and ant size are the two most important factors determining the number of feeding bouts that pangolins undertake on a particular ant species. Temperature effects on ant activity and their nest characteristics may exclude pangolins from parts of southern Africa.

No abstract

Aardwolves occur in east-central and southern Africa in regions of arid and semiarid grasslands. In South Africa, they feed almost exclusively on the termite Trinervitermes trinervoides during the warmer months of the year, whereas on cold winter nights these insects remain belowground, unavailable to aardwolves. At this time aardwolves shift their foraging efforts to a less abundant termite species, Hodotermes mossambicus. This species provides less food for aardwolves, making the wintertime potentially a period of energy stress for them.In this study, we report the first estimates of field metabolism and water flux as determined by doubly labeled water for a myrmecophagous euthermic mammal. Specifically, we tested the hypotheses that a reduced basal metabolic rate and pulmocutaneous water loss lead to a conservative field metabolic rate (FMR) and water flux in free-living aardwolves during summer and winter. Further, we quantified the activity budget of aardwolves during summer and winter to construct a time-energy budget for them. We used knowledge of water flux in aardwolves and of the water content of their prey to construct a water budget during summer and winter, and to estimate the seasonal consumption of termites by aardwolves.During summer (November-January), aardwolves that averaged 7768 g in body mass had a CO 2 production of 112.5 L CO 2 /d, equivalent to an energy expenditure of 2891.2 kJ/d. During winter (June-July), when body mass averaged 8543 g, CO 2 production averaged 71.8 L CO 2 /d, which translates to an FMR of 1844.8 kJ/d. Water flux equaled 615 mL/d in summer, but only 292 mL/d in winter, a decrease of 53.1%.Aardwolves were active for an average of 8.77 h/d in summer, but only 4.05 h/d during winter. A time budget for active periods showed that aardwolves spent a significantly larger proportion of their active time feeding in summer than in winter (26.7 vs. 15.2%). In addition, males and females spent 12.6% of their time in winter in breeding activities such as courtship and copulation. For aardwolves in summer, our model estimated a DEE of 2370.5 kJ/d, whereas during winter it predicted a DEE of 2086 kJ/d. These values deviated from our estimates of FMR by Ϫ18% and ϩ13.1%, respectively.From data on water flux and the water content of termites, we estimated that aardwolves consumed 222 445 Trinervitermes per night during the summer. Using previously obtained data on foraging, we predicted that aardwolves consume 833 termites per patch with an intake rate of 33 termites per second while feeding. During winter, aardwolves consumed 5867 Hodotermes and 2515 Trinervitermes per night. Our estimate of gross energy consumption was 5616 kJ/d in summer and 3022 kJ/d in winter. Assuming an assimilation efficiency of 0.66, metabolizable energy intake would be 3707 kJ/d in summer and 1995 kJ/d in winter. These values exceed FMR measurements by ϩ22% in summer and by ϩ8.1% in winter. It appears that aardwolves were in positive energy balance during our measurements of FMR.