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A retractable larynx and adaptations of the vocal folds in the males of several polygynous ruminants serve for the production of rutting calls that acoustically announce larger than actual body size to both rival males and potential female mates. Here, such features of the vocal tract and of the sound source are documented in another species. We investigated the vocal anatomy and laryngeal mobility including its acoustical effects during the rutting vocal display of free‐ranging male impala (Aepyceros melampus melampus) in Namibia. Male impala produced bouts of rutting calls (consisting of oral roars and interspersed explosive nasal snorts) in a low‐stretch posture while guarding a rutting territory or harem. For the duration of the roars, male impala retracted the larynx from its high resting position to a low mid‐neck position involving an extensible pharynx and a resilient connection between the hyoid apparatus and the larynx. Maximal larynx retraction was 108 mm based on estimates in video single frames. This was in good concordance with 91‐mm vocal tract elongation calculated on the basis of differences in formant dispersion between roar portions produced with the larynx still ascended and those produced with maximally retracted larynx. Judged by their morphological traits, the larynx‐retracting muscles of male impala are homologous to those of other larynx‐retracting ruminants. In contrast, the large and massive vocal keels are evolutionary novelties arising by fusion and linear arrangement of the arytenoid cartilage and the canonical vocal fold. These bulky and histologically complex vocal keels produced a low fundamental frequency of 50 Hz. Impala is another ruminant species in which the males are capable of larynx retraction. In addition, male impala vocal folds are spectacularly specialized compared with domestic bovids, allowing the production of impressive, low‐frequency roaring vocalizations as a significant part of their rutting behaviour. Our study expands knowledge on the evolutionary variation of vocal fold morphology in mammals, suggesting that the structure of the mammalian sound source is not always human‐like and should be considered in acoustic analysis and modelling., Male impala retract the larynx while producing their impressive rutting roars. The low fundamental frequency of these roars is produced by a highly modified vocal fold, a ‘vocal keel’. The anatomical and acoustical correlates of male impala's mobile larynx are discussed.

Loss of habitat is the main cause of species extinction, which today is 100 - 1000 times faster than the background extinction rate before the presence of mankind. One cause is that natural areas are being increasingly perturbed by roads, which degrades and fragments the habitat. In Tanzania, a proposed road through the Serengeti National Park (SNP) has caused international debate on whether it will cause irreversible damage to the ecosystem. I have assessed the current effect of roads and traffic on wildlife in the Serengeti, by using the impala (Aepyceros melampus) as a model species. I measured how faecal glucocorticoid metabolites (FGM), an indicator of stress levels, were affected by different road categories with different levels of traffic. Other stress related variables such as distance to the road, vegetation type and group size were accounted for. 196 faecal samples from 165 groups were collected over a 2 month-period from June – August 2012. FGM were measured using an enzyme immunoassay (EIA) validated for ruminants. I found that FGM levels were significantly increased near major roads with elevated levels of traffic compared to minor roads and side roads with less traffic in the Serengeti ecosystem. Predators, illegal hunting and social stress might also affect FGM levels in the impala, but these variables could not explain the variation observed. These results show for the first time that a large African mammal exhibit significant physiological stress in relation to roads. I argue that roads and traffic have the potential to cause major physiological stress in mammals, which in turn can affect the fitness of the organism. Care must be taken before implementing roads in protected areas, as increased disturbance can have severe consequences for the ecosystem if keystone species are affected. Future studies should assess the levels of stress wildlife can tolerate without it affecting fitness. Management plans for natural areas should include the possibility for increased physiological stress in animals living near major infrastructures and be proactive to ensure population and ecosystem viability.

Understanding how wildlife responds to road and traffic is essential for effective conservation. Yet, not many studies have evaluated how roads influence wildlife in protected areas, particularly within the large iconic African National Parks where tourism is mainly based on sightings from motorized vehicles with the consequent development and intense use of roads. To reduce this knowledge gap, we studied the behavioral response and local spatial distribution of impala Aepyceros melampus along the heterogeneous (with variation in road surface type and traffic intensity) road-network of Kruger National Park (KNP, South Africa). We surveyed different types of roads (paved and unpaved) recording the occurrence of flight responses among sighted impala and describing their local spatial distribution (in relation to the roads). We observed relatively few flight responses (19.5% of 118 observations), suggesting impalas could be partly habituated to vehicles in KNP. In addition, impala local distribution is apparently unaffected by unpaved roads, yet animals seem to avoid the close proximity of paved roads. Overall, our results suggest a negative, albeit small, effect of traffic intensity, and of presence of pavement on roads on the behavior of impala at KNP. Future studies would be necessary to understand how roads influence other species, but our results show that even within a protected area that has been well-visited for a long time, wildlife can still be affected by roads and traffic. This result has ecological (e.g., changes in spatial distribution of fauna) and management implications (e.g., challenges of facilitating wildlife sightings while minimizing disturbance) for protected areas where touristic activities are largely based on driving.

Summary Human-mediated changes in habitat structure may disturb predator–prey relationships. We investigated the influence of perimeter fences on the diet of a reintroduced population of African wild dogs Lycaon pictus Temminck 1820 in a 316 km2, fenced reserve in South Africa, by tracking radio-collared individuals during hunting periods to determine dietary composition from observed kills. Nutritional status of impala Aepyceros melampus and kudu Tragelaphus strepsiceros prey, as measured by the percentage of femur marrow fat, was significantly lower than that of unselectively culled individuals. This supports the hypothesis that wild dog predation is at least partially compensatory. Fence-impeded kills (those for which escape was deemed to be compromised by the fence) comprised 40·5% of kills (n = 316), and 54·1% of all edible biomass consumed. Compared with fence-unimpeded kills, fence-impeded kills comprised larger species (32·9 vs. 25·0 kg, W = 25667·0, P ≪ 0·001), older age classes for one prey category (female kudu: Fisher's exact test, P = 0·02, n = 65) and animals in better condition for adult impala males (Mann–Whitney, W = 111·0, P = 0·012, n = 28). Fence-impeded kills also provided greater catch per unit hunting effort (27·3 vs. 12·2 kg km−1; χ2 = 7·89, P = 0·005), resulting in longer interkill intervals. Movement of the pack towards the fence at the start of each hunting period suggested a decision to exploit the advantage that fences conferred for capturing prey. Synthesis and applications. By enabling coursing predators to capture prey that would otherwise have escaped, fences may reduce the compensatory nature of predation, causing shifts in predator–prey dynamics that could influence the ability of small reserves to support such predators. The establishment of larger conservation areas to reduce perimeter-to-area ratios should be encouraged to limit the undesired effects of fences on predator–prey dynamics.

Trophy hunting in ungulates may favour individuals with smaller horns. A decrease in horn/antler size may jeopardize the conservation potential of hunting areas, which would be a major concern in Africa where hunting zones represent over half of the total area of protected lands. We investigated horn length trends of harvested male impalas Aepyceros melampus, greater kudus Tragelaphus strepsiceros and sable antelopes Hippotragus niger, from 1974 to 2008 in Matetsi Safari Area, Zimbabwe. Horn length declined by 4% in impalas, partly because male harvest age decreased. In greater kudus, surprisingly, horn length increased by 14%, while mean age of harvested male greater kudus increased during the study period. Reduced hunting pressure on this species during the study may have allowed males to live longer and to grow longer horns before being harvested. Horn length declined by 6% in sable antelopes, independent of age, suggesting that trophy hunting selected male sable antelopes with smaller horns through time, provided that horn length is heritable. Hunting pressure and trophy value were higher for sable antelopes than for impalas and greater kudus. Accordingly, the decline of horn length in this species was more pronounced. More valuable trophy species, such as sable antelopes, require special attention because they may be exposed to higher hunting pressure, and are therefore more likely to experience a decrease in horn size. (Resume d'auteur)

Underlying mechanisms of sexual segregation amongst ungulates, and Trivers and Willard’s hypothesis that mothers can influence primary sex ratios, continue to be topical theoretical issues. Over two years, using monthly repeated road transects, we determined the habitat and social segregation of male versus female impala (Aepyceros melampus) and kudu (Tragelaphus strepsiceros) in a predator-free, versus a predator-laden, South African reserve. We also determined, by the same technique but over four years, the primary sex ratio of the impala population free from predation. Significant overlap in habitat usage (Schoener’s Index 0.63 to 0.8) was found between the two sexes when free from predation, but not (Schoener’s Index 0.46 to 0.47) when under predation. Whilst occupying the same habitats impala, kudu and wildebeest (Connochaetes taurinus) male and female groups maintained rigid social segregation throughout the year, even when at close quarters. Impala primary sex ratios were significantly biased towards females (male/female = 0.72; χ² = 4.3175, df = 1, p-value = 0.038) in the absence of predation. Our findings suggest that whilst risk of predation is a proximal cause of sexual segregation, thus lending support to the predator-risk hypothesis, the underlying, functional mechanism of sexual segregation is difference in the activity budgets of males versus females (the activity-budget hypothesis).Our findings also suggest that mothers may indeed be able to adjust primary sex ratios, with the postulated driver in this case being an abnormally high density of adult males.

International audience; In this study, we examined the behavioural, temporal and spatial effects of simulated African wild dog (Lycaon pictus) presence on its two main prey species: kudu (Tragelaphus strepsiceros) and impala (Aepyceros melampus). We spread African wild dog faeces around waterholes and played African wild dog sounds at different intervals to mimic immediate and non-immediate predation pressure. We looked at anti-predator behaviour at both a herd and individual level and distinguished between high-quality (detracts from all other activities), high-cost vigilance and low-quality (used to monitor the surrounding in spare time), low-cost vigilance to determine costs involved. We found that simulated African wild dog presence had little effect on anti-predator behaviour of their free-ranging prey. Only when immediate predation risk was mimicked did kudu invest in (additional) high-quality vigilance, whereas impala showed no response. Regardless of direct cues of African wild dog presence, behavioural adjustments to reduce predation risk were primarily based on environmental factors such as time of the day and broad-scale habitat structure. Predators have been shown to utilize waterholes to hunt, and prey species are therefore likely to maximize anti-predator behaviour in this high-risk environment based on environmental variables affecting predation risk, the main predator within the system, and water requirements, leaving little flexibility to respond to (simulated) African wild dog presence.

The late dry season is a crucial period for grazing ungulates because the nutritional value of the remaining brown grass is lowest then and levels of crude protein and digestible organic matter may fall below the maintenance requirements of herbivores (Owen-Smith, 1982). During this adverse period, mixed feeders like impala (Aepyceros melampus) increase the proportion of browse in the form of the leaves of the woody plants they consume (Owen-Smith & Cooper, 1985). Crude protein levels are generally higher and seasonally more constant in foliage of woody plants than in grasses (Owen-Smith, 1982), but the foliage is commonly defended by tannins or spines that restrict consumption by grazers not adapted to cope with them (Cooper & Owen-Smith, 1985, 1986; Cooper, Owen-Smith & Bryant, 1988). Sable antelope (Hippotragus niger) are predominantly grazers and are distributed throughout southern African savannahs (Estes, 1991; Skinner & Chimimba, 2005) where the dry season is prolonged and ambient temperatures are high before the rains begin. Grass quality is especially poor on infertile, sandy soils (Bell, 1984). Sable typically depend on green grass persisting in drainage sump grasslands or in recently burned areas during the dry season (Estes & Estes, 1974; Parrini & Owen-Smith, 2009). However, contrary to previous reports, we observed a substantial amount of browsing by sable in our study area during the dry season. Here, we quantify the contribution made by browse to the diet of sable in our study area. Methods

The factors that affect resource selection by a foraging herbivore can vary according to the resources or conditions associated with particular levels of organization in the environment, and to the scales over which the herbivore perceives and responds to those resources and conditions. To investigate the role of forage in this hierarchical process, we studied resource selection by a mixed-feeding large herbivore, the impala (Aepyceros melampus). We focussed on three spatial scales: plant species, feeding station and feeding patch. In paired sites where impala were and were not observed, we identified the plant species from which animals fed, the attributes of the plants, and the characteristics of the broader site. Across all three scales, plant species available as forage was central in determining resource selection by impala. At the species level, that effect was modified by the nutritional quality (greenness) and whether it was during a period of forage abundance or scarcity (season). At the feeding-station level, overall greenness and biomass of the station were important, but their effects were modified by the season. At the feeding-patch level, broader-scale factors such as the type of vegetation cover had an important influence on resource selection. The grass Panicum maximum was a preferred forage species and a key resource determining the locations of feeding impala. Our findings support the idea that selection by a foraging herbivore at fine scales (i.e. diet selection) can have consequences for broader-scale selection that result in observed patterns of habitat use and animal distribution.

Scat analysis is one of the most frequently used methods to assess carnivoran diets and Global Positioning System (GPS) cluster methods are increasingly being used to locate feeding sites for large carnivorans. However, both methods have inherent biases that limit their use. GPS methods to locate kill sites are biased towards large carcasses, while scat analysis over-estimates the biomass consumed from smaller prey. We combined carcass observations and scats collected along known movement routes, assessed using GPS data from four African lion (Panthera leo) prides in the Kruger National Park, South Africa, to determine how a combination of these two datasets change diet estimates. As expected, using carcasses alone under-estimated the number of feeding events on small species, primarily impala (Aepyceros melampus) and warthog (Phacochoerus africanus), in our case by more than 50% and thus significantly under-estimated the biomass consumed per pride per day in comparison to when the diet was assessed using carcass observations alone. We show that an approach that supplements carcass observations with scats that enables the identification of potentially missed feeding events increases the estimates of food intake rates for large carnivorans, with possible ramifications for predator-prey interaction studies dealing with biomass intake rate.

The distribution and abundance of native ungulates were measured on commercially managed, semi-arid rangeland in central Kenya over a 3-year period that encompassed severe drought and above-average rainfall. Native ungulate biomass density averaged 5282 kg km )2 over the study and was dominated by elephant (Loxodonta africana), impala (Aepyceros melampus) and dik-dik (Madoqua kirkii). Biomass density of domestic cattle (Bos taurus) averaged 2280 kg km )2 during the study. Responses of native ungulates to severe drought were variable. Impala densities were similar to or greater than densities for similar habitat in protected areas, and varied from 12 to 16 km )2 during and following the drought to 24–29 km )2 following above-average rainfall. Dik-dik densities were also greater than densities reported for protected areas and were surprisingly stable throughout the study despite the wide annual fluctuations in rainfall. Elephant migrated out of the region during drought but were present at high densities (2.9–5.2 km )2 ) during wet seasons, consistent with telemetry studies emphasizing the importance of Acacia bushland habitat on commercial rangelands for the migratory portion of the Laikipia–Samburu elephant population. Results show that substantial densities of native browsing and mixed-feeding ungulates can occur on rangeland managed for commercial beef production and suggest that the capacity for ungulates to move over large spatial scales (>100 km 2 ) and to shift distributions in re

Wild impala display a highly reciprocal allogrooming system that, by virtue of its frequency and high degree of reciprocity, is unique among ungulates. A herd of 35 free-ranging captive impala provided opportunity to examine the degree of reciprocity of allogrooming exchanges and the influence of relatedness, dominance, age and association on partner preferences and distribution of grooming between allogrooming partners. As in wild impala, the exchange of allogrooming bouts in the captive impala was highly reciprocal regardless of partners. Kinship and dominance had no influence on partner preference or distribution of grooming between partners. Although mothers showed a significant preference to allogroom with their unweaned offspring, this preference practically disappeared with older offspring. Age-mates (no greater than 6 mo apart) tended to associate with one another and spatial proximity was positively correlated with grooming partner preference. It was not clear whether impala actively sought out age-mates for grooming, or randomly chose grooming partners from nearby age-mates. The failure to find a role for kinship and dominance is counter to what has generally been found in most Old World terrestrial primate studies. The absence of pronounced social influences, coupled with the known effectiveness of grooming in removing ectoparasites, suggest that a utilitarian role, especially removal of ticks, is an important function of the impala reciprocal allogrooming system.

Adult impala engage in a form of reciprocal allogrooming distinguished by a high degree of reciprocity and ***lack of influence of dominance or relatedness on partner preference or distribution of grooming between partners. A previous study on reciprocal allogrooming of captive newborn impala lambs in a zoological park found that the allogrooming emerged as early as the first week after birth and was identical in structure and reciprocity to allogrooming in adults. Because these findings of apparently unique allogrooming behavior of newborn impala could have been a reflection of the effects of being born and raised in a small, stable captive herd, it was necessary to investigate reciprocal allogrooming in newborn impala in the wild. The emergence, reciprocity, rate, and partner distribution of reciprocal allogrooming in wild newborn impala were observed at two study sites: a national park in Zimbabwe and a game farm in South Africa. Maternal one-way grooming between mother and newborn emerged as distinct from reciprocal allogrooming and rapidly declined after week 1 postpartum. Reciprocal allogrooming by lambs was first seen between 5 and 8 d postpartum, and as soon as the behavior occurred it was the same basic pattern as seen in adult impala. The reciprocity index for lambs was near 0.5, indicating that lambs delivered as much grooming during an encounter as the partner. Lambs were grooming frequently with non-mother adults and other lambs by week 1 or 2; by week 3 and onward the allogrooming rate of lambs was more than twice that of their mothers, as predicted by the body size principle of the programmed grooming model. The strong predisposition of neonatal impala lambs to deliver reciprocal allogrooming as early as the first or second week postpartum would appear to reflect a genetically acquired adaptation to the threat of tick infestation in their natural habitat.

Among adult females and males of African antelope impala are unique in their performance of reciprocal allogrooming. The occurrence of this behaviour in neonatal impala fawns was explored in a free-ranging impala herd at the San Diego Wild Animal Park where 5 dam-reared fawns were observed from birth through 10 weeks of age. One-way maternal grooming and reciprocal allogrooming with the dam and non dam partners emerged as distinct behavioural systems. Maternal grooming, directed mostly to the anogenital area, was typical of that seen in other ungulates, and sharply declined over the first two weeks. Reciprocal allogrooming, characterized by alternate exchanges of grooming bouts with a partner in the same manner as in adults, was seen as early as 3–8 d after birth. All fawns were grooming with unrelated adult females by the end of the second week. By week 2 virtually every measure of reciprocal allogrooming by fawns (grooming delivered per hour, reciprocity, and percent of encounters initiated) was as high as for adults. The appearance of this reciprocal allogrooming pattern, especially at such an early age, appears to be unique among ungulates, and possibly mammals in general. Three hand-reared impala fawns, deprived of the opportunity to interact with older herdmates, but having access to impala fawns and heterospecific fawns, were observed from 1–3 mo of age. The hand-reared impala showed no alteration in the occurrence of reciprocal allogrooming behaviour compared with the dam-reared control fawns, indicating that allogrooming experience with older animals was not required for the appearance of reciprocal allogrooming at an early age. Interestingly, hand-reared fawns persisted in grooming heterospecific fawns despite the fact that heterospecifics rarely reciprocated grooming. We postulate that the strong predisposition for impala young to groom others may be related to the threat of tick infestation in the impala's ecotone habitat.

We investigated herd-sizes and herd-compositions of Impala (Aepyceros melampus) inside a protected area [Lake Mburo National Park (LMNP) in western Uganda] and the unprotected adjacent ranchland [the Ankole Ranching Scheme (ARS)]. Impala experience intense hunting and poaching in the study area, and poaching is especially strong on the ARS. We found evidence for changes in overall group-sizes in both mixed-sex and pure bachelor herds between areas in and outside LMNP. Mixed-sex herds strongly decreased in size outside the National Park, but bachelor herds even slightly increased in size. While the group-composition of mixed-sex herds was very similar in areas in and outside LMNP, bachelor herds comprised more yearlings and subadult males on the ARS. Our study suggests that effects of hunting and other human nuisance may differ between herd types: mixed herds probably decrease in size because females are more strongly hunted. Around LMNP, impala are usually hunted using nets and spears, thereby increasing the hunters’ chance of being injured. Poachers therefore prefer hornless females (and their calves), as it is less dangerous to handle net-caught females than males. As a result, males are less hunted, but increased vigilance and, therefore, reduced aggression among the members of a bachelor herd, may account for the observed increase in herd sizes and changes in group-compositions. Resume Nous avons etudie la taille et la composition des hardes d’impalas (Aepyceros melampus) dans une aire protegee, le Parc National du Lac Mburo (LMNP) dans l’ouest de l’Ouganda, et dans le ranch adjacent non protege, le Ankole Ranching Scheme (ARS). Les impalas subissent une chasse et un braconnage intenses dans la region etudiee et le braconnage est particulierement grave dans l’ARS. Nous avons decouvert des preuves de changement de la taille moyenne des groupes, aussi bien dans les hardes mixtes que dans celles composees uniquement de mâles, entre les aires situees dans et en dehors du LMNP. La taille des hardes mixtes diminuait fortement hors du parc national alors que les hardes composees de mâles augmentaient legerement. Alors que la composition des groupes mixtes etait tres semblable dans et en dehors de l’aire protegee, les groupes de mâles comprenaient plus de jeunes de l’annee et de subadultes dans l’ARS. Notre etude laisse penser que les effets de la chasse et des autres nuisances d’origine humaine pourraient differer selon le type de harde: la taille des hardes mixtes se reduit probablement parce que les femelles sont chassees davantage. Autour du LMNP, les impalas sont d’habitude chasses au moyen de filets et de fleches, ce qui augmente les risques que les chasseurs soient blesses. Les braconniers preferent donc les femelles, sans cornes, et leurs jeunes parce qu’il est plus facile de manipuler des femelles prises dans des filets que des mâles. Par consequent, les mâles sont moins chasses, et une plus grande vigilance et donc une moins forte agression entre les membres d’une harde de mâles peuvent expliquer en partie pourquoi la taille des hardes augmente et la composition des groupes varie.

Stable isotope analysis of tooth enamel was used to investigate the relative proportions of grass and browse in seasonal and overall diets of impala Aepyceros melampus at Akagera National Park, Rwanda. Bulk enamel samples suggest that on average, impala ate c. 86% C4 grass year-round, far more than in most previously studied impala populations across Africa. Intra-tooth samples show that seasonal changes in the proportion of C4 grass versus C3 browse are minimal (c. 10%), the diet being dominated by C4 grass year-round in contrast to other impala populations that consume ≥50% browse during the dry season. Intra-tooth oxygen isotope values track carbon isotope changes to a moderate degree, but are not patterned clearly enough to permit identification of wet versus dry seasons. As other studies have shown that impala select high-protein diets, the foraging behaviour at Akagera is probably because of the availability of palatable grass for much of the year in the edaphic grasslands around the lacustrine environments of the eastern portions of Akagera National Park. Resume L’analyse des isotopes stables de l’email des dents a servi pour etudier les proportions relatives d’herbes et d’autres matieres vegetales dans le regime alimentaire saisonnier et general de l’impala Aepyceros melampus au Parc National de l’Akagera, au Rwanda. Des echantillons d’email suggerent qu’en moyenne, les impalas mangent c. 86% d’herbes de type C4 tout au long de l’annee, beaucoup plus que la plupart des populations d’impalas etudiees ailleurs en Afrique. Les echantillons du centre des dents montrent que les changements saisonniers de la proportion d’herbes de type C4 par rapport au type C3 sont minimaux (c. 10%) et que le regime alimentaire est domine par des herbes de type C4 toute l’annee, contrairement aux autres populations d’impalas qui consomment ≥50% d’autre vegetation pendant la saison seche. Les valeurs de l’isotope d’oxygene dans les dents permettent, dans une faible mesure, de detecter des changements de l’isotope de carbone, mais ils ne sont pas suffisamment definis pour permettre l’identification des saisons seches ou humides. Comme d’autres etudes ont montre que les impalas selectionnent une alimentation riche en proteines, le comportement alimentaire des impalas a l’Akagera est probablement dua la disponibilite d’herbes gouteuses pendant une grande partie de l’annee dans les prairies edaphiques qui entourent les environnements lacustres de l’est du Parc National de l’Akagera.

Fecal glucocorticoid metabolite (FGM) assays are a popular means of monitoring adrenocortical activity (i.e., physiological stress response) in wildlife. Species-specific differences in glucocorticoid metabolism and excretion require assay validation, including both laboratory and biological components, before assay use in new species. We validated a commercially available radioimmunoassay (MP 125I corticosterone RIA kit [MP Biomedicals, Solon, OH]) for measuring FGMs of several South African herbivores, including giraffe (Giraffa camelopardalis), impala (Aepyceros melampus), nyala (Tragelaphus buxtoni), kudu (Tragelaphus strepsiceros), wildebeest (Connochaetes taurinus), and zebra (Equus burchelli). These herbivores are important in South African parks and reserves for ecotourism and as a prey base for predators and serve an integral role in ecosystem processes. Standard biochemical validations (e.g., recovery of exogenous corticosterone, intra- and interassay variation, and parallelism) demonst...

Groupforagingcanbebeneficialforungulatesbydecreasing the time required for vigilance, but it can also prove costly because of competition. To determine responses to gregarious behaviour, we studied foraging activity and vigilance of impala (Aepyceros melampus) near Kruger National Park, South Africa. We measured time spent foraging, vigilant, moving, grooming, engaging in social interactions and determined herd size and group distribution (i.e. density). We calculated accepted food abundance (AFA), food ingestion rate, steps per minute and percent vigilance for female, bachelor male and herd male impala. There was no relationship between herd size and vigilance, but vigilance decreased with increasing density (t1,311 = 4.91, P < 0.0001). Additionally, AFA decreased (t1,61 = 5.96, P < 0.0001) and steps per minute increased (t1,311 = 14.38, P < 0.0001) as more individuals fed in close proximity to each other. Impala could be altering their behaviour to accommodate a perceived change in resources because of intraspecific competition and these adjustments might be related more to the distribution of herd members than to herd size. Further studies should examine the behaviour of gregarious animals in relation to the distribution of herd members in addition to group size.

Summary 1 Top-down regulation of ecosystems by large herbivores is a topic of active debate between scientists and managers, and a prime example is the interaction between elephants Loxodonta africana and trees in African savannas. A common assumption among wildlife managers is that a local reduction in elephant numbers will ultimately allow woodland to self-restore to a desired former state. Such regeneration is, however, dependent on the survival of seedlings of impacted tree species. We conducted a field experiment to investigate seedling predation in the elephant-transformed Chobe riparian woodland of northern Botswana. 2 We planted seedling gardens in (i) complete exclosures that excluded all herbivores except small rodents and invertebrates, (ii) semi-permeable exclosures that excluded ungulates but included primates, lagomorphs, all rodents, gallinaceous birds, etc, and (iii) completely open plots. Seedlings were of two tree species decreasing in the area (Faidherbia albida and Garcinia livingstonei) and two that are increasing (Combretum mossambicense and Croton megalobotrys). 3 After 9 months, seedling survival ranged from >75% for all species in the complete exclosure to

This study compares two methods of estimating the density of three ungulate species: Kirk’s dik-dik, impala and common zebra, in a dry savannah ecosystem. Fixed strip width and distance sampling involving direct animal counts were used in parallel, and tested for bias and precision in two habitats. Distance sampling was the method that achieved a better balance between accuracy and precision. The differences in sightability of ungulates, according to body size, colour and habitat characteristics, are taken into account by the distance sampling method, but not by the strip method, which produced, what we suspect are, underestimates of animal density. Resume Cette etude compare deux methodes pour estimer la densite de trois especes d’ongules : le dik-dik de Kirk, l’impala et le zebre de Burchell, dans un ecosysteme de savane seche. On a utilise en parallele l’echantillonnage par largeur de bande fixe et celui a distance perpendiculaire, impliquant le comptage direct des animaux, et nous avons teste les biais qu’ils induisent et leur precision dans deux habitats. L’echantillonnage a distance perpendiculaire fut la methode qui a obtenu le meilleur equilibre entre exactitude et precision. Les differences de visibilite des ongules, selon la taille corporelle, la couleur et les caracteristiques de l’habitat, sont prises en compte par la methode a distance mais pas par la methode par bande qui entraine, nous le suspectons, des sous-estimations de la densite animale.

The phylogeography of the bush habituated African bovid species impala ( Aepyceros melampus ) and greater kudu ( Tragelaphus strepsiceros ) is investigated using mitochondrial DNA (mtDNA) markers. Combined analysis of individual lineages, relationships and population genetics suggest a colonization process from Southern Africa toward Eastern regions in the greater kudu. Results are less clear for the impala, although remaining consistent with a similar pattern of historical dispersion. The study reveals a similar pattern, that is a marked divergence of lineages from South-western Africa relative to other regions. This pattern is opposed to previously published findings in other African bovid species. In the impala, the genetically isolated region is consistent with morphology because it is recognized as the subspecies A. m. petersi , the black-faced impala. In contrast, the similar split of South-western mitochondrial lineages was not expected in the greater kudu on the basis of morphology. Both species show a significant population genetic differentiation. Beyond their phylogeographical value, our results should raise conservation concerns about South-western populations of both species. The black-faced impala is categorized as vulnerable and our data show indications of hybridization with common impala A. m. melampus . The previously unrecognized genetic status of the South-western kudus could also imply conservation regulations.

Species become endangered primarily through population decline-for example, because of extensive poaching. Conservation generally begins with protection from causes of decline. Subsequent steps may include (1) translocation to protected areas, especially where the cause of decline is local overhunting and/or habitat loss, and (2) establishment of international restrictions on trade. Paradoxically, such well-intentioned efforts can create new threats for the species. Translocation, or the intentional movement and release of animals in the wild, can be an important conservation tool, used to increase the number of individuals, genetic variability, and gene flow and to redistribute populations to areas of optimal habitat (Franzmann 1988; Griffith et al. 1989; Gripps 1991; Caughley 1994). Efforts to save endangered species have involved translocation from the natural range to similar areas nearby, where causes of decline are absent (Conant 1988). On the other hand, translocations involving introduction of exotic species generally result in serious problems for management and conservation (Scheffer 1994; Arano et al. 1995). Hybridization is likely when translocation allows contact between closely related taxa (Robinson et al. 1991; Rhymer & Simberloff 1996). For rare endemics, the threat posed by genetic swamping may be as great as that of population decline. Restrictions placed on importation of endangered species and products (e.g., hunting trophies) to other countries represent an attempt to reduce the value of endangered species as commodities by prohibiting trade in and use of these animals. In some circumstances, these controls actually hinder management and conservation of endangered species within their native countries. The case of the black-faced impala (Aepyceros melampus petersi) in Namibia illustrates potential problems inherent in translocation and import restrictions. We explore two of these problems: (1) loss of unique genotypes due to translocation-caused contact between previously allopatric taxa and (2) economic disincentives, caused by a U.S. ban on imports, for private landowners to maintain pure herds of black-faced impala. Black-faced impala are an endangered subspecies (World Conservation Union 1973; U.S. Department of the Interior 1980), differing from common impala (Aepyceros melampus melampus) in body size, coloration, facial markings, and habitat (Swart 1967; Haltenorth & Diller 1986; Skinner & Smithers 1990). Blackfaced impala are endemic to a small region in northwestern Namibia and southwestern Angola (Gaerdes 1965; Smithers 1983; East 1989). Recent reports indicate that they are nearly extinct in Angola (Huntley & Matos 1992; World Conservation Union 1992). In Namibia the natural range of the black-faced impala (Fig. 1) is in Kaokoland (Opuwo district), a communal area on the Angolan border (Swart 1967; Joubert 1971). Kaokoland is a remote, arid, mountainous region inhabited by nomadic pastoralists, the Ovahimba and Herero (Jacobsohn 1990). Kaokoland was previously renowned for its wildlife (Bigalke 1958) and set aside as a protected reserve in 1928, when it was part of Etosha National Park. At the same time it served as a reserve for the Himba and Herero (Owen-Smith 1972; Malan 1974). In 1970 Kaokoland lost its protected status. Today, little remains of its wildlife. Hunting pressure increased during the war between the South West Africa People's Organization and the South African Defense Force, when the latter issued thousands of rifles and ammunition to local people (Walker 1978; Owen-Smith 1986; Hall-Martin et al. 1988; Lindeque 1990). During this time, Kaokoland was devastated by the worst drought on record; in addition to wildlife, more than 80% of the cattle died (Owen-Smith 1986; Loutit & Owen-Smith 1989).

We investigated the variation in birth synchrony displayed by impala Aepyceros melampus populations across their distribution from southern to eastern Africa. Our analysis was based on field data from Chobe National Park in Botswana and Mala Mala Private Game Reserve in South Africa (4 and 13 years of monitoring, respectively). We compared our results with those from other studies conducted across the impala species range. Impala lambing was highly synchronized in Chobe with 90% of lambs born within 2 weeks in mid-November. Variation in rainfall in the preceding wet season explained 74% of variation in the dates of the first lamb observation in Mala Mala. In Chobe, the earliest birth peak occurred after the highest rainfall and the body condition of lambs in that cohort was also best for both males and females. No association was found between the lunar cycle and the estimated onset of the conception period, despite previous studies having found an association between the lunar cycle and the rutting behaviour in males. On a regional scale, impalas in areas with a marked dry season (several months with no rain) tend to synchronize births with the onset of the rains, when grass quality is highest. Number of months with rain explained 78% of the regional variation in birth synchrony. Neither latitude nor total rainfall contributed significantly to a stepwise multiple regression model. These data support the theory that impalas synchronize births in areas with a highly seasonal food supply, and temporally space births in less seasonal (equatorial) areas to reduce predation risks.

The single species of Aepyceros, Aepyceros melampus (impala), is native to central and southern Africa, from Uganda to South Africa. It inhabits open woodlands, sandy bush country and acacia savannah. This study tested the morphological and geographical variation among specimens of impala and their possible relation with described subspecies. Nineteen skull and horn measurements were taken. A multivariate analysis was used and size and shape were explored. Facial coat patterns were also coded. The results supported four out of five traditionally described subspecies: Aepyceros melampus petersi from Angola/Namibia, Aepyceros melampus melampus from South Africa, Aepyceros melampus suara from East Africa and Aepyceros melampus johnstoni from Zambia and Malawi. We consider Aepyceros melampus rendilis to be a synonym of suara. A revised synopsis is suggested, with comments on the geographical ranges of the subspecies. Skull dimensions also allowed us to estimate the geographical origin and subspecies of some individuals of unknown provenance. Coat patterns showed no clear relation with subspecies or geographic location, with the exception of A. m. petersi.

The use of home ranges and microhabitats by female black-faced impalas Aepyceros melampus petersi was investigated using radio-telemetry over a 4-month period that coincided with parturition at Ongava Game Reserve, north-west Namibia. The aim of the study was to test how ranging patterns and microhabitat use were affected by the presence of young. The mean minimum convex polygon (MCP) home range of the 11 tracked female black-faced impalas exceeded the largest of home ranges of impalas elsewhere by at least six times, and females used significantly larger total ranges (MCPs) after birth, although (50% kernel) core areas did not change significantly. Females were more likely to be solitary or alone with a lamb in the first week of their lambs' lives than in the periods after or before that time, and they both shifted their home ranges and changed their microhabitat use after parturition. Decisions on microhabitat and space use by female black-faced impalas appeared to be affected by parturition.

The role of territoriality was investigated by studying 25 impala rams at a reserve in the Waterberg region of South Africa (23°45′S, 28°23′E). Mean territorial tenure was 67.25 days (range 23–99), with a mean territory size of 21.0 ± 11.27 ha, compared with home ranges of 34.1 ± 9.03 ha for territorial rams and 58.8 ± 33.35 ha for bachelor rams, using the fixed kernel method. Territory boundaries remained constant, whilst the area surrounding important features such as water holes, appears to be neutral in terms of territoriality. The rut, as evidenced from peaks in chasing and roaring, lasted for 2 months from 10 April to 10 June 2001, with intensified behaviour including matings observed from 16 May to 4 June 2001. Territorial rams chase and roar more than bachelors. Flehmen and display behaviours are performed by all rams, whilst fights and other reproductive behaviours are generally rare. Bachelors browse more than territorial rams. Only bachelors spar and allogroom, and orally groom themselves more than territorial rams. Resume On a etudie le role de la territorialite en observant 25 mâles impala dans une reserve de la region de Waterberg, en Afrique du Sud (23°45′S, 28°23′E). La conservation d'un territoire durait en moyenne 67,25 jours (23–99 jours) et celui-ci mesurait en moyenne 21.0 ± 11.27 ha, compare au domaine vital qui est de 34.1 ± 9.03 ha pour les mâles territoriaux et de 58.8 ± 33.35 pour les jeunes mâles solitaires, en utilisant la methode de Kernel. Les limites des territoires restaient constantes, alors que l'aire entourant les elements importants comme les points d'eau semble neutre en termes de territorialite. Le rut, mis en evidence par des pics de poursuites et de cris, a dure deux mois (10 avril – 10 juin 2001) et ce comportement s'est intensifie, avec des accouplements observes entre le 16 mai et le 4 juin. Les mâles territoriaux se lancent dans des poursuites et des cris plus que les solitaires. Le flehmen behaviour et les exhibitions sont pratiques par tous les mâles, alors que les combats et les autres comportements reproducteurs sont en general rares. Les celibataires broutent plus que les mâles territoriaux. Seuls les celibataires feignent des combats et se grooment l'un l'autre, et ils se grooment eux-memes avec la bouche plus souvent que les mâles territoriaux.

In constructing large vegetated mounds, Macrotermes termites play a key functional role in many African savanna systems. This study focuses on ungulate feeding on Macrotermes termitaria vegetation in Lake Mburo National Park, Uganda. With the exception of oribi Ourebia ourebi, all the species studied (i.e. impala Aepyceros melampus, Burchell's zebra Equus burchelli, Defassa waterbuck Kobus ellipsiprymnus, topi Damaliscus lunatus, bushbuck Tragelaphus scriptus and warthog Phacochoerus africanus) grazed preferentially on mound areas compared to the adjacent savanna. Ruminant species grazed closer to termitaria than non-ruminants and female impala both browsed and grazed closer to mounds than males. No sexual difference in grazing distance to mounds was found for waterbuck.

Along the Chobe Riverfront in northern Botswana, elephants Loxodonta africana have reduced woodland cover and modified woody species composition, forming shrublands. We tested the hypothesis that this has favoured the impala Aepyceros melampus population and contributed to the observed population increase by creating more available dry-season browse. Our results suggest that the increasing Capparis shrubland represents a key browsing habitat. The mixed Combretum shrubland was a less important browsing habitat, as female impalas browsed proportionally to the time spent feeding, but this habitat has more than doubled in extent, to almost 60% since 1962, thus providing much more available browse. The Baikiaea woodland, which has declined to less than half of its extent during 1962–1998 mainly due to elephant impacts, provided the least amount of dry-season browse for impalas. Impalas browsed mostly below 70 cm and conversion of woodland to shrubland has increased the availability of browse at this h...

One of the advantages of living in groups is that individuals may need to be less vigilant, allowing them more time for other important activities, such as foraging. This relationship between group size and per cent time spent being vigilant was investigated by observing impala in Nairobi National Park, Kenya. Three types of individual were observed: females, territorial males and bachelor males. Only females showed the predicted negative relationship between per cent vigilance and herd size. Both types of male showed no significant change of vigilance with increasing group size. There was no difference in levels of vigilance in open or closed habitats and no difference in vigilance between herds ‘alone’ and herds with other species that might have provided ‘extra eyes’.

Physical morphological measurements and m longissimus lumborum proximate chemical composition of impala (Aepyceros melampus) and the effects of age, sex and region on these parameters were investigated. Impala were randomly sampled from Mara (n = 40, 24 males, 16 females), situated in the Arid Sweet Bushveld region, and Musina (n = 28, 15 males, 13 females), situated in the Mopane Bushveld region in the Limpopo Province of South Africa. The live weights of the Mara (50.23 ± 9.32 kg) animals were higher (p < 0.05) than those of the Musina animals (44.25 ± 10.81 kg). The male animals from both regions were significantly heavier than the females (p < 0.05), particularly for the older animals (∼5 kg for 30-month-old animals and ∼10 kg for 42-month-old animals); however, the dressing percentages between the sexes did not differ. The Mara female group (∼62%) had significantly (p < 0.05) higher mean dressing percentages than the Musina females (∼58%). The mean proportions of external and internal offal were relatively higher in the Musina animals. No significant differences in the dressing percentages between the five age groups were found. Carcass measurements increased linearly with age. Age showed no effect on the m longissimus lumborum chemical carcass composition. Female animals (∼19.4 g kg) had higher (p < 0.05) lipid contents for both regions than the males (∼14.0 g kg) but the sex of the animal had no effect on the remaining chemical carcass composition parameters. The crude protein content of the Musina animals (248.8 ± 10.44 g kg) was higher (p < 0.05) than for the Mara animals (238.0 ± 8.404 g kg). The mean ash content of the impala m longissimus lumborum was ∼12 g kg. The results indicated that age effects are caused by the increases in size brought about by the growth of the animal and by the development of sexual dimorphism. Age, however, had no effect on the m longissimus lumborum proximate chemical composition. Regional differences were also shown for both the physical parameters as well as for the proximate chemical composition of the muscle. Similarly, females also differed from males for the parameters measured. These factors will have to be taken into consideration by the meat trade when purchasing, processing and marketing impala game meat.

In sub-Saharan Africa, the widespread practice of corralling livestock overnight in thorn-scrub “bomas” creates nutrient-enriched patches within rangelands that can subsequently support unique plant communities for decades to centuries after boma abandonment. These nutrient-rich patches (glades) may be preferentially used by native ungulates that coexist with livestock. To evaluate the potential link between cattle management via bomas and habitat for impala (Aepyceros melampus), I examined seasonal patterns of habitat selection by impala and landscape variation in grass nutrient content on a commercial cattle ranch in central Laikipia, Kenya. Studies using automated, infrared camera monitors showed that impala selected nutrient-rich glades 2.6 times more frequently than surrounding Acacia bushland habitat during dry seasons, and 9.6 times more frequently during wet seasons. Significantly greater impala presence in glade versus bushland habitat during dry seasons suggests that impala presence may...

Wildlife Ranching South Africa (WRSA). Patent applications : ZA2014/05233, ZA2015/03778 and PCT/IB/2015/055391.

Cheetah Acinonyx jubatus home-range size and habitat use were analysed using radio-tracking data collected in the southern district of the Kruger National Park (KNP) between 1987 and 1990. Meaningful estimates of home-range size, using the 95% minimum convex polygon method, were 126 km2 for a three-male cheetah coalition, 195 km2 for a solitary male, and 150 km2 and 171 km2 for two female cheetahs. Although cheetahs used all habitats according to their availability, they did show a preference for open savanna habitat because their core or total home ranges centred on these habitats. Female cheetahs used denser woodland habitat more frequently than males, as they seemed to be influenced by the distribution of their main prey, impala Aepyceros melampus, which also preferred denser woodland habitat.

The impact of fire on the foraging behaviour of impala (Aepyceros melampus), was studied in the Lake Mburo National Park, Uganda. Two indices of foraging efficiency were used to establish differences in feeding behaviour in burnt and unburnt control areas. These are acceptable grass/browse abundance (AGA/ABA), expressed in terms of feeding time achieved per 50 steps and food ingestion rate (FIR), expressed as the cumulative percentage. Accumulation of above ground grass biomass was also measured in burnt and control areas. After burning, the grazing efficiency remains constant throughout the dry season, while the browsing time achieved per 50 steps decreases drastically. In the control areas AGA decreased with increasing length of the dry season while ABA increased. When expressed in terms of cumulative percentage (FIR), the results show a significant increase of 31% in foraging time spent grazing and a 24% decrease in foraging time spent browsing, in burnt areas. The results confirm the classification of impalas as intermediate or mixed feeders with a distinct preference for grass. Impala foraging patterns after burning are discussed and compared with investigations on the effect of burning on the behaviour of impalas and Buffon's kob (Kobus kob kob) in other areas of Africa. Resume NdT : En francais, la distinction entre paitre et brouter est loin d'etre aussi evidente qu'entre le graze et le browse anglais. Par commodite, nous employons ici paitre pour traduire graze (et pâturage pour grazing), c'est-a-dire manger de l'herbe, et brouter pour traduire browse, c'est-a-dire manger des feuilles, des rameaux, des brindilles et aussi, a l'occasion, de l'herbe. On a etudie l'impact des feux sur les habitudes alimentaires des impalas (Aepyceros melampus) du Parc National du Lac Mburo, en Ouganda. On a utilise deux indices d'efficacite de l'alimentation pour etablir des differences d'habitudes alimentaires dans des aires brulees et des aires de controle non brulees : l'indice acceptable grass/browse abundance (AGA/ABA) qui exprime le temps passea se nourrir pour 50 pas, et l'indice food ingestion rate (taux d'ingestion de la nourriture) (FIR), exprime comme le pourcentage cumulatif. On a aussi mesure l'accumulation de la biomasse herbeuse au-dessus du sol dans les zones brulees et dans les zones controle. Apres les feux, l'efficacite du pâturage reste constante pendant toute la saison seche alors que le temps passea brouter pour 50 pas diminue fortement. Dans les aires de controle, la valeur d'AGA diminue avec l'augmentation de la duree de la saison seche alors que la valeur d'ABA augmente. Lorsqu'on les exprime en termes de pourcentages cumulatifs (FIR), les resultats montrent une augmentation significative de 31% du temps passea paitre et une diminution de 24% du temps passer a brouter dans les zones brulees. Les resultats confirment la classification des impalas parmi les animaux a alimentation intermediaire ou mixte, la prioriteetant distinctement accordee a l'herbe. On discute du schema de l'alimentation des impalas apres les feux et on le compare avec les recherches sur l'effet des feux sur le comportement des impalas et des cobes de Buffon (Kobus kob kob) dans d'autres regions d'Afrique.

Intersexual and seasonal variation in foraging behaviour of impala (Aepyceros melampus), was studied in the Lake Mburo National Park, Uganda. There was a moderate seasonal difference in foraging efficiency (as measured by ‘acceptable food abundance’), with a minimum in dry season and a maximum in Rainy season. The variation between sexes was more distinct with a pronounced minimum in time spent browsing of males in early wet season. By distinguishing between feeding time spent grazing and feeding time spent browsing the seasonal variation was confirmed. The proportion of foraging time spent feeding (expressed as ‘food ingestion rate’) showed an inverse pattern with a maximum in the late dry season (75.5%), decreasing values throughout the Rainy season and a minimum in early dry season (57.8%). Differences between sexes were explained in terms of reproductive demands and seasonal balance in terms of moderate climate throughout the year. Impala foraging patterns in the bimodal tropics (two Rainy seasons) is discussed and compared with unimodal tropics. The findings are matched against current ideas on optimal foraging.

The intraocular pressure and rate of tear production were measured in 18 addax antelopes (Addax nasomaculatus), four impalas (Aepyceros melampus), 11 wide-lipped rhinoceroses (Ceratotherium simum), 10 white-tailed wildebeests (Connochaetes gnou) and seven scimitar-horned oryxes (Oryx dammah). The animals were anaesthetised with an intramuscular injection of etorphine hydrochloride and acepromazine maleate, and the Schirmer tear test I was used to evaluate tear production, and applanation tonometry was used to evaluate the intraocular pressure. The mean (sd) rate of tear production ranged from 17.6 (3.1) mm/minute in the rhinoceros to 28.8 (8.3) mm/minute in the addax. The intraocular pressure ranged from 8.0 (1.2) mmHg in the impala to 32.1 (10.4) mmHg in the rhinoceros. The rate of tear production in the addax and the intraocular pressure in the rhinoceros appear to be the highest values of these variables to have been reported in any species.

Body mass is often considered as a good indicator of body condition of individuals in ungulates, hence of their fitness, and thus, may be used as an index to monitor the status of populations subject to harvesting schemes. Here, we report the influence of annual rainfall (a proxy for primary production) and habitat on the body mass of impala in a population cropped for meat in a communal area of Zimbabwe. We analyzed the data from 2 contrasted years for rainfall, in two different habitats. In the good year (i.e. high annual rainfall) impala were heavier than in the poor year, and adult females seemed to be less affected than males by variation in primary production. We show that adult males were suffering from a seasonal decrease in body mass, supposedly linked to the rut, particularly in good habitat. Overall, the habitat effect appeared to be dominated by the rainfall effect, and this may be due to the very high animal densities in the good habitat, i.e. fast resource depletion. Our results also suggest that males (juvenile and adult) are more susceptible to changes in food resource abundance and quality than females, which supports previous studies on sexually dimorphic and polygynous species. Resume On considere souvent que la masse corporelle est un bon indicateur de la condition physique chez les ongules, et donc de leur bon etat general; on peut donc s'en servir comme index pour controler le statut des populations qui font l'objet d'un programme de prelevements. Nous rapportons ici l'influence des chutes de pluies annuelles (qui sont liees a la production primaire) et de l'habitat sur la masse corporelle des impalas d'une population ou l'on preleve des animaux pour la viande, dans une aire communale au Zimbabwe. Nous avons analyse les donnees de deux annees contrastees pour les chutes de pluies, dans deux habitats differents. La bonne annee (c.-a-d. fortes chutes de pluies), les impalas etaient plus gros que la mauvaise annee, et les femelles adultes semblaient moins affectees que les mâles par les variations de la production primaire. Nous montrons que les mâles adultes subissaient une reduction saisonniere de leur masse corporelle, sans doute liee au rut, et surtout dans les bons habitat. Partout, l'effet de l'habitat semble etre surpasse par l'effet des chutes de pluie, et ceci est peut-etre dua la tres forte densite des animaux dans le bon habitat, c.-a-d. un rapide epuisement des ressources. Nos resultats suggerent aussi que les mâles, juveniles et adultes, sont plus sensibles que les femelles aux changements dans l'abondance et la qualite des ressources alimentaires, ce qui confirme des etudes anterieures sur les especes dimorphiques et polygames.

This investigation analyses the commercial carcass yields and chemical composition of impala (Aepyceros melampus). The potential of this species for the export market is also discussed. Impala rams (eight) and ewes (eight) cropped commercially in Zimbabwe were found to have a similar dressout proportion (580 g kg), although the males had a heavier live weight (49.4 ± 4.606 kg) than the females (33.5 ± 3.417 kg). Sexual dimorphism was shown, with the males having significantly (p 0.2) were found in the mean chemical proximate composition of the 9-10-11 rib cut for the moisture (724.0±14.00g kg pooled sample), protein (238.3 ± 7.46 g kg pooled sample) and ash (21.2 ± 3.74 g kg pooled sample) contents. The females had a statistically higher (p = 0.0197) mean total lipid content (33.9 ± 1.705g kg) than the males (24.5 ± 3.171 g kg). This investigation occurred at the end of the impala rut season, a period when the rams not only consume less feed but also expend more energy owing to strenuous activities in fighting for and maintaining a harem. (C) 2000 Society of Chemical Industry.

The study was done in Lake Mburo area, Uganda, consisting of Lake Mburo National Park and surrounding ranches. The study involved monitoring changes of output of helminth eggs per gram (e.p.g.) by impala for 12 months. Fresh faecal samples, 178 in total, were collected from the rangeland and subjected to floatation and culture tests. There was a peak faecal e.p.g. output from March to April and from October to November. This period coincided with time of high rainfall and calving peak of impala. There was no faecal e.p.g. observed during the dry spell from June to July. Resume Cette etude fut menee dans la region du Lac Mburo en Uganda, comprenant le Lake Mburo National Park et les ranchs avoisinants. Elle a implique la surveillance continue des variations de l’expulsion d’oeufs d’helminthes par gramme (e.p.g.) par les impalas durant 12 mois. Au total, 178 echantillons fecaux frais furent collectes dans la zone d’etude et soumis a des tests de flottation et de culture. On a constate un pic d’expulsion d’e.p.g. fecaux de mars a avril et d’octobre a novembre. Cette periode coincidait a l’epoque des fortes pluies et du pic des mises bas de l’impala. On n’a observe aucune e.p.g. fecale durant la periode seche de juin a juillet.

The small population of wild dog Lycaon pictus (n= 3 to 30) in Hluhluwe-Umfolozi Park (HUP) has declined since 1992. The survival of dogs in HUP is dependent on the reintroduction of more dogs; however, wild dog reintroduction programmes are fraught with problems and many have failed. In this paper the diet and capture success of the wild dog pack in the Hluhluwe Section, and the influence of dietary considerations on the success of the future reintroduction of wild dogs in this reserve, are investigated. Diet choice was determined from scat analysis, personal observation and field staff records. Eight ungulate prey species were identified from scat analysis: nyala Tragelaphus angasi and impala Aepyceros melampus were the most abundant ungulate species in HUP and accounted for 77% of the diet. On the whole, wild dogs included prey types in the diet consistent with a rate-maximizing foraging approach, although some prey were clearly taken opportunistically. The dogs preyed mostly on small- (> 25 kg) to medium-sized (40–90 kg) prey, while the young of large (< 90 kg) prey species or scavenged carcasses supplemented the diet during the dry season. Adult nyala were taken more frequently than other age classes, but wild dog preyed on juvenile impala more than expected. Female prey were taken more frequently than males but selection did not differ from prey population sex ratios. Prey capture success was similar to that of previous studies from both open and densely wooded habitats and the wild dogs successfully caught 48% of all prey species pursued. Results suggest that wild dogs are quite capable of adapting both their diet choice and foraging technique to the dense vegetation in HUP. We conclude that prey type, prey availability and habitat constraints on prey capture success, will not affect the reintroduction of more wild dogs into HUP.

Summary A study of habitat selection by oribi (Ourebia ourebi, Zimmermann 1783), a small antelope in northern Serengeti National Park, Tanzania, addressed two questions: (1) what were the most preferred habitat features? and (2) did oribi associate with or avoid other ungulates? These questions were pertinent to three hypotheses on the function of habitat selection in antelopes: (i) habitats are chosen to minimize the cost of obtaining resources, (ii) habitat selection results from niche partitioning due to interspecific competition, or (iii) habitat selection functions to avoid predation by using escape terrain and by associating with other species for protection. Results from transects designed to examine preferences for open grassland, Acacia woodlands, Combretum-Terminalia woodland, forests, thickets and rocky habitat types suggested that oribi preferred habitats with rocky outcrops and Combretum-Terminalia woodland. These habitats supported preferred food plant species consistent with hypothesis (i). However, oribi occurred close to rocks in the dry season, and in areas with long grass during the wet season, both of which are used for cover against predators. The significant association of oribi with larger resident ungulates [impala (Aepyceros melampus) and kongoni (Alcelaphus buselaphus)] also suggested that oribi were avoiding predators, consistent with hypothesis (iii). Oribi avoided wildebeest, possibly because of interference, but were randomly associated with topi, zebra and Thomson's gazelle. Preference for plateaux or gentle slopes and green flush agree with studies elsewhere. Major contrasts were shown in the avoidance of open grasslands and Themeda triandra which are reported to be favoured by most oribi populations in South Africa. Resume Une etude de la selection de ľhabitat par ľoribi, Qurebia ourebi, Zimmermann 1783, une petite antilope du nord du Pare National du Serengeti, en Tanzanie, cherchait a repondre a deux questions: (1) Quels sont les elements preferes de ľhabitat? et (2) Est-ce que ľoribi s'associe ou evite les autres ongules? Ces questions se rapportaient a trois hypotheses sur la fonction de la selection de ľhabitat par ľoribi: (i) Ľanimal choisit ľhabitat pour reduire le cout de ľobtention de nourriture. (ii) La selection de ľhabitat resulte du partage des niches, suite aux competitions interspecifiques. (iii) La selection de ľhabitat sert aeviter les predateurs grâce a ľexistence de terrains de secours ou aľassociation avec ?autres especes dont ils obtiennent la protection. Des circuits furent choisis pour examiner les preferences entre les herbages ouverts, les zones boisees ?Acacia de Combretum-Terminalia, les forets, les buissons ou les endroits rocheux. Les resultats suggerent que ľoribi prefere les habitats avec des surplombs rocheux et ceux peuplees de Combretum-Terminalia. Dans ces habitats poussent les especes vegetales preferees, ce qui repond aľhypothese (i). Cependant, on rencontre des oribis pres des rochers en saison seche et dans les zones couvertes ?herbes hautes en saison des pluies, les deux milieux servant de protection contre les predateurs. Ľassociation significative des oribis aves des ongules plus grands comme ľimpala, Aepyceros melampus, ou le bubale, Alcelaphus buselaphus, suggere aussi que les oribis evitent les predateurs, ce qui repond aľhypothese (iii). Les oribis evitent les gnous, peut-etre en raison ?interferences, mais sont parfois associes aux topis, aux zebres et aux gazelles de Thomson. La preference pour les plateaux, les pentes douces et les ilots de verdure concorde avec ?autres recherches. Les plus grandes differences concernent le fait qu'ils evitent les pâturages ouverts et Themeda traindra qui sont recherches, parait-ill, par la plupart des populations ?oribis en Afrique du Sud.

Casual observations have revealed that the anterior dentition of impala and other antelope is loosely embedded, with the tips of the teeth movable over a distance of 1middot;5 to 2mm. The comb-like anterior dentition of impala Aepyceros melampus is utilized extensively for grooming purposes, and it was hypothesized that the looseness of the teeth might be related to the grooming function. A sample of 12 impala mandibles was obtained from Pilanesberg National Park. Boputhatswana. Six of the incisor canine (IC) complexes were examined macroscopically, radiographically and histologically, while the remaining six were used to determine the alveolar depth relative to total root length, The findings were: (1) wide periodontal ligament spaces, most prominent in the apical region; (2) a loose, highly vascular periodontal ligament; (3) well-developed trans-septal periodontal ligament fibres; and (4) relatively shallow alveoli, with only approximately two-thirds of the roots included within the alveoli. In no case could looseness be ascribed to pathological changes in the periodontal ligament, cementum or alveolar bone. These features suggest that the looseness of the teeth is associated with a see-saw action of the teeth about a fulcrum below the alveolar bone crest. with the maintenance of the closed resting position of the teeth being facilitated by the well-developed trans-septal fibres. It is suggested that the minimal interdental space maintained by this arrangement during grooming assists in the efficient removal of parasites from the pelage by impala.

Because impala are commonly exhibited and handreared in zoos and their natural nursing behavior had not previously been studied, we examined nursing and early development in five impala calves housed in a large, naturalistic enclosure. Calves were observed for the first 5 weeks of life during 12-hr continuous watches and 20-min focal animal samples. Total daily suckling time decreased while time grazing and feeding on concentrates increased from 1–5 weeks of age. An increasing proportion of nursing bouts were terminated by the dam as calves matured, with dams terminating almost 70% of bouts during the first week. Suckling success and maternal grooming also decreased after week I, suggesting that impala mothers cut back early on nursing and grooming of offspring. Rapid decline in mother-young spatial proximity and a concomitant increase in calf association with age-mates over time suggests that the mother-young bond is weak and ephemeral in impala. An example of the implications of our results for improving handrearing programs would be that newborn calves should be started on a daylight feeding schedule of one bottle-feeding every three hours, and that they not be allowed to gorge themselves at any one of these feedings.

Two impala (Aepyceros melampus) carcasses were subjected to varying degrees of mutilation by large mammalian scavengers. Daily observations of carcass surface condition revealed that the timing and frequency of scavenger feeding visits had a profound effect upon carcass decomposition: a single feeding visit 10 days after death at the first carcass produced an extended sequence of decay. At the second carcass, repeated visits two, three and five days after death, resulted in a faster rate of decay. The colonization of the carcasses by necrophagous insects was characterized by a distinct sequence of arrival. The abundance of Calliphoridae, Histeridae and Dermestidae was correlated with surface condition at both carcasses. Thus, these insects provided an indication of the state of carcass decay. However, as the rate of decomposition was different at each carcass, the temporal abundance of necrophagous insects was not the same at both carcasses. The results suggest that the temporal abundance of key insect families provide an inaccurate indication of the time of death in circumstances when carcasses have subsequently been mutilated.

The physiological response resulting from manual restraint in veld and bomakept impala was investigated by determining haematocrit, lactate, glucose, total protein and lipid, osmolarity, cortisol, and catecholamine values at times 0, 5, and 10 minutes. Blood was also obtained at time 10 from animals manually restrained but without repetitive sampling. The results indicate that manual restraint resulted in a physiological response in both veld and boma-kept animals but that the reactions were different depending on whether the impala were naive. In addition, repetitive blood sampling did not aggravate the response.