Abstract. Following the recent invasion of bovine tuberculosis (BTB) into the Kruger National Park, South Africa, we conducted a study on the maintenance host, African buffalo, to investigate associations between BTB prevalence and calf:cow ratio, age structure, body condition, and endoparasite load. Statistical analyses compared herds of zero, medium (1-40%), and high (Ͼ40%) BTB prevalence. To control for ecological variation across the park we collected data in northern, central, and southern regions and restricted some analyses to particular regions of the park. Body condition declined over the course of the 2001 dry season, and buffaloes in the southern region of the park, with the highest BTB prevalence, were in worse condition than buffaloes in the northern region (which receives less annual rainfall but is still virtually BTB-free). Herd-level analyses of the entire park, the south and central regions, and just the southern region all indicated that herds of higher BTB prevalence were in worse condition and lost condition faster through the dry season than herds of lower BTB prevalence. Fecal endoparasite egg counts increased during the dry season and were associated with both decreased body condition and increased BTB prevalence. Although we did not detect any obvious effect of BTB on the age structure of the buffalo population, our findings indicate early symptoms of wider scale BTB-related ecological disturbances: buffalo herds with high BTB prevalence appear more vulnerable to drought (because of a decrease in body condition and an increase in endoparasite load), and because lions selectively kill weak buffaloes their prey base is accumulating a disproportionately high prevalence of BTB, to which lions are susceptible.

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal of Animal Ecology.Aberdeen AB9 2QJ, UK Summary 1. Group hunting in social carnivores is generally thought to have evolved through natural selection for improved efficiency of prey capture, increased prey size apprehended or defence of the kill against intra-and interspecific kleptoparasitism. 2. We used a simple model to explore how variation in hunting group size of wild dogs in the Serengeti influences defence of kills against kleptoparasitism from spotted hyenas and the trade-off effects this has on intake rate per dog for a given prey size selected. The analysis presented suggests that while kleptoparasitism substantially influences the amount of time a hunting group can access a kill, increases in access time with increased hunting group size rarely fully compensate for the reduction in each dog's share of the carcass due to scramble competition among the dogs. 4. A profitability index, which includes limitations of the probability of capturing different sized prey, gut capacity, food depletion and access time, suggests that smallhunting groups (1-2) would be particularly vulnerable to kleptoparasitism because they are unable to fully satiate themselves before spotted hyenas take over their kills. Intermediate-sized hunting groups may be most effective at meeting nutritional demands over a range of prey sizes. 5. While reasons for the recent extinction of the Serengeti wild dog population remain speculative, this paper contributes to the debate by proposing that kleptoparasitism by spotted hyenas would have placed a major constraint on the ability of individual wild dog packs to recover from episodic disasters.

postal address: tshwane university of technology, private bag X680, pretoria, 0001, south africa abstract during the past several years, non-invasive monitoring of steroid metabolites in faeces of elephants has become an increasingly popular technique to generate more information about the causal relationship between hormones and behaviour in both living elephant species. this is important knowledge which can be used to optimise local conservation and wildlife management by finding new strategies for better elephant population management and control. in this context, however, information about an actual involvement of the hypothalamic-pituitary-adrenal axis during assumable stressful events is still limited, especially for wildlife populations. One difficulty in discovering such information is often the lack of reliable data for hormone baseline levels. therefore, the aim of this study was to determine baseline concentrations of faecal glucocorticoid metabolites that could be expected within age classes and between seasons in african elephants (Loxodonta africana) in the kruger national park (knp). a total of 374 faecal samples were collected from randomly located family herds in the southern knp between may 2002 and august 2005. the samples were analysed for immunoreactive concentrations of faecal glucocorticoid metabolites using a validated enzyme immunoassay for 3α,11oxo-cortisol metabolites (3α,11oxo-Cm). all samples were grouped according to the estimated age class of the subject using a field method based on bolus diameter, and regarding the ecological season collected. No significant differences in faecal 3α,11oxo-Cm concentrations were found across age classes (H 3 = 7.54; p = 0.057), but the mean 3α,11oxo-Cm concentration of samples collected in the dry season (n = 196) was significantly higher than in the wet season (n = 178) (u = 15206.50; p = 0.032), which indicates a possible physiological stress situation due to a decline in food quantity and quality. the information generated in this study represents a reliable data set for baseline concentrations of faecal glucocorticoid metabolites for elephants within the knp and can be used to measure the stressrelated effects of translocations, management actions and the impact of chosen land use activities.

Stokke, S. and du Toit, J. T. 2000. Sex and size related differences in the dry season feeding patterns of elephants in Chobe National Park, Botswana -Ecography 23: 70-80.Differences in feeding patterns of the African elephant were examined by sex and age during the dry season in a dystrophic savanna-woodland ecosystem in northern Botswana. Adult males had the least diverse diet in terms of woody plant species, but they consumed more plant parts than family units. The diameter of stems of food plants broken or bitten off was also greater for adult males than for females and subadult males. Adult males spent more time foraging on each woody plant than did females. The number of woody plant species and individuals present were higher at feeding sites of family units than at feeding sites of adult males, indicating that family units positioned themselves at feeding sites with higher species diversity than those of males. We argue that the most likely explanation for these differences is related to the pronounced sexual size dimorphism exhibited by elephants, resulting in sex differences in browsing patterns due to the allometric relationships that govern the tolerance of herbivores for variation in diet quality. From our results this Body Size Hypothesis is accepted rather than the alternative Scramble Competition Hypothesis, which predicts that adult male elephants consume lower quality browse because they are displaced from preferred browse as an outcome of scramble competition with adult females and their offspring. If the feeding patterns of adult male elephants were affected by intersexual scramble competition, we would expect adult males to browse at a higher level in the canopy than the smaller-bodied females and their offspring. No evidence was found for this, although adult females were found to browse at a higher level in the canopy when feeding in close proximity to subadults and juveniles than when feeding alone. Sex differences in elephant browsing patterns are, we propose, of relevance to understanding and managing elephant impacts on African woodlands.