Springbok Antidorcas Marsupialis Research Articles

Keeping cool on hot days: activity responses of African antelope to heat extremes

Long-lived organisms are likely to respond to a rapidly changing climate with behavioral flexibility. Animals inhabiting the arid parts of southern Africa face a particularly rapid rise in temperature which in combination with food and water scarcity places substantial constraints on the ability of animals to tolerate heat. We investigated how three species of African antelope—springbok Antidorcas marsupialis, kudu Tragelaphus strepsiceros and eland T. oryx—differing in body size, habitat preference and movement ecology, change their activity in response to extreme heat in an arid savanna. Serving as a proxy for activity, dynamic body acceleration data recorded every five minutes were analyzed for seven to eight individuals per species for the three hottest months of the year. Activity responses to heat during the hottest time of day (the afternoons) were investigated and diel activity patterns were compared between hot and cool days. Springbok, which prefer open habitat, are highly mobile and the smallest of the species studied, showed the greatest decrease in activity with rising temperature. Furthermore, springbok showed reduced mean activity over the 24 h cycle on hot days compared to cool days. Large-bodied eland seemed less affected by afternoon heat than springbok. While eland also reduced diurnal activity on hot days compared to cool days, they compensated for this by increasing nocturnal activity, possibly because their predation risk is lower. Kudu, which are comparatively sedentary and typically occupy shady habitat, seemed least affected during the hottest time of day and showed no appreciable difference in diel activity patterns between hot and cool days. The interplay between habitat preference, body size, movement patterns, and other factors seems complex and even sub-lethal levels of heat stress have been shown to impact an animal's long-term survival and reproduction. Thus, differing heat tolerances among species could result in a shift in the composition of African herbivore communities as temperatures continue to rise, with significant implications for economically important wildlife-based land use and conservation.

Factors affecting the prey preferences of jackals (Canidae)

Prey selection by carnivores can be affected by top-down and bottom-up factors. For example, large carnivores may facilitate food resources for mesocarnivores by providing carcasses to scavenge, however mesocarnivores may hunt large prey themselves, and their diets might be affected by prey size and behaviour. We reviewed jackal diet studies and determined how the presence of large carnivores and various bottom-up factors affected jackal prey selection. We found 20 studies of black-backed jackals (Canis mesomelas) from 43 different times or places, and 13 studies of Eurasian golden jackals (Canis aureus) from 23 different times or places reporting on 3900 and 2440 dietary records (i.e. scats or stomach contents), respectively. Black-backed jackals significantly preferred small (<30kg) ungulate species that hide their young (duiker Sylvicapra grimmia, bushbuck Tragelaphus scriptus and springbok Antidorcas marsupialis), and avoided large (>120kg) hider species and follower species of any body size. They had a preferred and accessible prey weight range of 14–26kg, and a predator to ideal prey mass ratio of 1:3.1. Eurasian golden jackal significantly prefer to prey on brown hare (Lepus europaeus; 4kg), yielding a predator to preferred prey mass ratio of 1:0.6, and a preferred and accessible prey weight range of 0–4kg and 0–15kg, respectively. Prey preferences of jackals differed significantly in the presence of apex predators, but it was not entirely due to carrion availability of larger prey species. Our results show that jackal diets are affected by both top-down and bottom-up factors, because apex predators as well as prey size and birthing behaviour affected prey preferences of jackals. A better understanding of the factors affecting jackal prey preferences, as presented here, could lead to greater acceptance of mesocarnivores and reduced human-wildlife conflict.

Prey preferences of free‐ranging cheetahs on farmland: scat analysis versus farmers' perceptions

AbstractHuman–predator conflict is one of the biggest threats to large carnivore species worldwide. Its intensity is closely linked to farmer's attitudes and perceptions of predators. As a result, farmers' estimates of the number of livestock or game‐stock animals killed by predators are often formed based on the perceived number of predators present and their perceivably favoured prey species. This study aims to examine the prey preferences of cheetahs Acinonyx jubatus in relation to farmers' perceptions and the relative contribution of livestock and game‐stock to the cheetahs' diet. Cheetahs' prey preferences were determined through the cross‐sectional analysis of prey hair, found in cheetah scat. Cheetahs were found to predominantly prey on free‐ranging abundant game species, primarily kudu Tragelaphus strepsiceros. Game ranchers overestimated the prominence of game‐stock to the cheetahs' diet, especially springbok Antidorcas marsupialis. Potential reasons for these discrepancies and the importance of abundant natural prey as a potential human–predator coexistence strategy are discussed.

A breath test to assign carnivore diets to browsers or grazers

Cheetahs Acinonyx jubatus are important predators of herbivores in African ecosystems, and several methods to determine their diet have been used in the past. We applied a novel method to quickly assess the diet of cheetahs with respect to grazing and browsing herbivores, i.e. we analysed the stable carbon isotope ratio (δ13CV‐PDB) of cheetah breath to separate individuals feeding predominantly on browsers or grazers, respectively. Browsers and grazers are contrasting in their muscle δ13CV‐PDB, because of their isotopically distinct C3 or C4 plant diet, respectively. Muscle δ13CV‐PDB of six abundant local potential prey species of cheetahs confirmed that kudu Tragelaphus strepsiceros and springbok Antidorcas marsupialis browsed on C3 plants, whereas gemsbok Oryx gazella, hartebeest Alcelaphus buselaphus, warthog Phacochoerus africanus and cattle Bos taurus predominantly grazed on C4 plants. Breath δ13CV‐PDB of the cheetahs followed the bimodal frequency distribution of the prey species with six cheetahs being assigned to the C4 food web and three to the C3 food web. Breath tests may be a suitable method to delineate the trophic membership of carnivores to C3 and C4 food webs when animals are chemically immobilised for other purposes.

Prey selection and prey preferences of spotted hyenas Crocuta crocuta in the Etosha National Park, Namibia

AbstractThe feeding ecology of the spotted hyena Crocuta crocuta was studied in the central and eastern part of the Etosha National Park, Namibia. Hyenas mainly hunted migratory ungulates such as springbok Antidorcas marsupialis, zebra Equus burchelli, and blue wildebeest Connochaetes taurinus, but also resident species such as the greater kudu Tragelaphus strepsiceros and gemsbok Oryx gazella. There were, however, major differences in the species most frequently killed by hyenas in central and eastern Etosha. The preferred prey species of spotted hyenas in central Etosha was springbok, whereas regarding the abundance of zebra and wildebeest, these two species were rather avoided. In contrast, the prey species preferred by hyenas in eastern Etosha was kudu. Zebra and gemsbok were taken in proportion to their abundance, whereas wildebeest and springbok seemed to be rather avoided. Differences in prey selection and preferences were also reflected in differences in hunting group sizes. In eastern Etosha, where spotted hyenas frequently hunted larger prey, hunting group sizes were significantly larger compared to those in the center of the park.

A year in the thermal life of a free-ranging herd of springbokAntidorcas marsupialis

We used miniature data loggers implanted in the abdominal cavity to measure core body temperatures at 30 min intervals in eight (three males, five females) adult free-ranging springbok Antidorcas marsupialis in their natural habitat, over a period of 11-13 months. The animals were subjected to a nychthemeral range of air temperature that often exceeded 20 degrees C, with an absolute minimum temperature of -6 degrees C and a maximum of 34 degrees C. Abdominal temperature exhibited a low amplitude (approximately 1.2 degrees C) nychthemeral rhythm, with a temperature peak near sunset and a trough shortly after sunrise. The amplitude of the nychthemeral rhythm of body temperature was not correlated with the 24 h range of air temperature. Although mean 24 h body temperatures were positively correlated with corresponding air temperatures, mean daily body temperature increased, on average, by only 0.02 degrees C per 1 degrees C increase in air temperature, so that it was only approximately 0.3 degrees C higher in summer than in winter. Mean monthly body temperatures were strongly positively correlated with photoperiod and, in parallel with changes in the time of sunrise, the times at which the minimum and maximum body temperatures occurred were shifted approximately 1.2 h earlier in summer than in winter. Annual and daily variations in body temperature of springbok, like those of other free-living African ungulates, therefore appear to reflect an endogenous rhythm, entrained by the light:dark cycle, but largely independent of fluctuations in the environmental thermal load. Springbok exhibit remarkable homeothermy and do not employ adaptive heterothermy to survive in their natural environment.

Spotted hyenas (Crocuta crocuta) follow migratory prey. Seasonal expansion of a clan territory in Etosha, Namibia

AbstractThe spatial organization of one clan of spotted hyenas Crocuta crocuta in the centre of the Etosha National Park, Namibia, is described during the dry and the wet seasons. The clan comprised 11 adults and sub‐adults and occupied a territory of 160 km2 in the dry season and 320 km2 in the wet season. The dry season territory contained a low density (one animal/km2) of resident herbivores, such as gemsbok Oryx gazella, kudu Tragelaphus strepsiceros, giraffe Giraffa camelopardis, steenbok Raphicerus campestris and ostrich Struthio camelus, and a higher density of migratory species (12 animals/km2), principally springbok Antidorcas marsupialis, zebra Equus burchelli and wildebeest Connochaetes taurinus. These migratory species were the main prey of clan members. At the start of the wet season, the migratory herbivores migrated to the north‐west, resulting in a considerable decline in the density of prey in the area used by clan members during the dry season. In response to this decline in prey, clan members followed the migratory herds and shifted the focus of their activities to an area grazed by migratory herbivores during the wet season. There existed a strong spatial relationship between the hyena density and the migratory prey density in both the dry and wet season. We postulate that the considerable enlargement of the clan territory in the wet season is a response to both the migratory movements of prey and an increase in the dispersion of prey during the wet season.

Fluctuating asymmetry and allozyme variability in an isolated springbok Antidorcas marsupialis population from the Chelmsford Nature Reserve

Allozyme variability and fluctuating asymmetry (FA) in skull morphology were used to test the hypothesis of inbreeding in an isolated springbok Antidorcas marsupialis (Zimmermann, 1780) population from the Chelmsford Nature Reserve, South Africa. Of 39 loci studied in a sample of 30 animals, five displayed allelic polymorphism. Average heterozygosity of 1.8% was not appreciably lower than a value of 2% calculated for 49 animals from a control group from Benfontein Game Farm in the Northern Cape Province, South Africa. Proportion of polymorphic loci and average number of alleles per locus were identical in both populations (10.3% and 1.1). Morphological analysis contradicted the prediction of increased fluctuating asymmetry due to the likelihood of inbreeding in a small, isolated population, with FA almost always higher in the control compared to Chelmsford. Chelmsford animals were however smaller than control animals for seven out of 9 cranial and horn variables analysed (significantly so in four cases), hich could conceivably be explained by environmental influences. It is concluded that loss of genetic diversity is not a problem in the Chelmsford springbok population, although this does not negate the possibility that physical deformities occurring in the population may indeed be genetically induced.

Large trees, fertile islands, and birds in arid savanna

LargeAcacia eriolobatrees scattered through the sparse grassy vegetation of arid oligotrophic savanna are focal points for animal activity because they supply nest sites, shade and scarce food resources. Faeces, fallen nest material and carcass remains left below trees elevate levels of nutrients available to plants in the soil beneath large trees. Soil concentrations of N and K were two times greater, and P concentrations 2.055 times greater under canopies ofA. eriolobatrees than in surrounding grassy shrubland.Plant species with fleshy fruits (Boscia, Grewia, LyciumandSolanumspp.) occurred in 8% of treeless plots and beneath 17% ofA. eriolobasaplings, but their frequency increased to 90% beneath large trees. DeadA. eriolobatrees were replaced by matrix vegetation (54%) and large shrubs with fleshy fruits (28%) rather than by conspecifics (17%). The distribution of fleshy-fruited plants in the Kalahari is thus dynamic and tied to the distribution of large trees such asAcacia erioloba.The shade beneath the canopies of large spreading trees was used by birds (particularly Kori BustardsArdeotis kori) and mammals (mainly SpringbokAntidorcas marsupialis, GemsbokOryx gazella, Blue WildebeestConnochaetes taurinusand Bat-eared FoxOtocyon megalotis) as a resting place during the heat of the day. Large raptors (> -031.055 kg) and vultures (> -035 kg) seldom perched on saplings, and more frugivorous bird species and individuals were seen on mature than sapling or dead trees. Nests of raptors, and the large communal nests of Sociable WeaversPhiletarius sociuswere found mainly in large trees, and the nests of the Tree RatThallomys paedulcuswere found in cavities in the stems of large trees.

The effect of stress and season on some Haematological and Biochemical parameters of three antelope species in the Kalahari Gemsbok National Park

A seasonal study of some haematological and biochemical parameters of three antelope species (springbok Antidorcas marsupialis, oryx Oryx gazella and blue wildebeest Connochaetes taurinus) was conducted during January, April and June in the Kalahari Gemsbok National Park. A communal increase in two blood parameters during April was observed in all three species studied. These increases correlated with optimal range conditions. Active pursuit of individuals as well as drug induced immobilisation proved to place animals under stress influencing haematograms extensively.

Features of habitat selection by larger herbivorous mammals and the Ostrich in the Southern Kalahari conservation areas

A Chi-squares contingency table was used to extensively analise animal/habitat interactions in the southern Kalahari conservation areas between 1978 and 1982. The effect of changing environmental con-&#x0D; ditions on the distribution of five large mammalian species (eland Taurotragus oryx, gemsbok Oryx gazella, blue wildebeest Connochaetes taurinus, red hartebeest Alcelaphus buselaphus, springbok Antidorcas marsupialis) and the ostrich Struthio camelus is indicated by definite seasonal preferences. A general habitat-use pattern, whereby each habitat type was utilised at some stage during the year by one or more species, as well as a response by the different species to other environmental attributes was found revealing an ecological balance which will be maintained only if the present physical size of the conservation areas in question is maintained indefinitely.

Prey selection and feeding habits of the large carnivores in the Southern Kalahari

Prey selection and feeding habits of lions Panthera leo, spotted hyaenas Crocuta crocuta, cheetahs Acinonyx jubatus and leopards Panthera pardus are investigated. Lions kill mainly adult gemsbok Oryx gazella and blue wildebeest Connochaetes taurinus, tending to select older animals of both species and males in the case of gemsbok. Spotted hyaenas also prey mainly on gemsbok and wildebeest, but select for juveniles, particularly from gemsbok. Cheetahs prey heavily on springbok Antidorcas marsupialis lambs and then on adult males and older individuals. Leopards also prey relatively heavily on springbok, but appear to have a wider diet than cheetahs do. It is concluded that predators generally have a small impact on their prey populations in the southern Kalahari, although in the case of springbok they do appear to influence the structure of the population.

The response of ungulates to rainfall along the riverbeds of the Southern Kalahari

The responses of springbok Antidorcas marsupialis, gemsbok Oryx gazella, blue wildebeest Connochaetes taurinus and red hartebeest Alcelaphus buselaphus to rainfall along the riverbeds of the southern Kalahari are analysed. Springbok reacted most rapidly to rainfall along the riverbeds and, by browsing in dry times, maintained a fairly stable presence throughout the year, although the actual number present in any one year was dependent on annual rainfall. Gemsbok responded more slowly to rainfall and reached their highest numbers in years of high rainfall when the grasses were tall and mature, after which they rapidly departed from the riverbeds. Red hartebeest also reached their highest numbers during the rainy season, but departed slightly more slowly than gemsbok. In dry years, they too, failed to come into the riverbeds. Blue wildebeest in the vicinity of the riverbeds tended to be more sedentary than the other species. The presence of potable artificial water appeared to be more important for wildebeest than for the other species and, although rainfall was undoubtedly an important factor in regulating their numbers along the riverbeds, they depended to a greater extent on breeding success and mortality factors, than on emigration and immigration. The overall seasonal pattern of ungulate abundance along the riverbeds in the southern Kalahari was one of wet season concentrations and dry season dispersion.

The effect of windmill closure on the movement patterns of ungulates along the auob riverbed

Three groups of six consecutive windmills along the Auob riverbed were closed down for periods of one year and the responses of the three major ungulate species in the area to this practice were studied. The movements of springbok Antidorcas marsupialis and gemsbok Oryx gazella were not found to be affected by the windmill closure, but blue wildebeest Connochaetes taurinus showed significant tenden- cies to move out of areas in which windmills were closed.

Adaptations in three species of large mammals (Antidorcas marsupialis, Hystrix africaeaustralis, Hyaena brunnea)to arid environments

Adaptations in the springbok Antidorcas marsupialis, porcupine Hystrix africaeaustralis and brown hyaena Hyaena brunnea to arid environments are discussed. Springbok evolved in the arid west of southern Africa. The proximate factor triggering the onset of oestrus is improved nutrition following rainfall and adaptations have evolved to ensure the success of year-round opportunistic breeding. The porcupine can also breed throughout the year but in the Karoo with its dry cold winters, young are only born in warmer wetter months. Following a gestation period of 93 days and lactation anoestrus lasting 120 days, the female porcupine has evolved a special adaptation whereby she will only conceive during the third to seventh oestrous cycle following the end of lactation. This period may be shortened or lengthened thereby enabling her to adjust to climatic conditions in an unpredictable arid environment. The brown hyaena is well adapted to living along the Namib coastal region where severe extremes in temperature occur and bitterly cold south-west winds sweep along the coastal strip. Long hair and pilo-erection probably assist brown hyaenas in adjusting to these adverse climatic conditions. The spotted hyaena, Crocuta crocuta, does not occur along the coast. Morphological differences between the two species are considered in the light of climatic differences between the coastal and interior desert regions.

The Vegetation of the S. A. Lombard Nature Reserve and its Utilisation by Certain Antelope

The S.A. Lombard Nature Reserve is situated about 12 miles west of Bloemhof, Western Transvaal. The reserve is flat open country with a gentle slope to the east and south. Abandoned alluvial diamond diggings which run from north to south divide the reserve into a western and an eastern area which are geologically different. The region is open grass land with small patches of bush, classified as dry Cymbopogon-Themeda veld. The food habits of black wildebeest Connochaetus gnou, blesbok Damaliscus dorcas phillipsi, Cape eland Taurotragus oryx, Cape oryx Oryx gazella, impala Aepyceros melampus, red hartebeest Alcelaphus buselaphus, and springbok Antidorcas marsupialis were studied over the three year period, 1958 to 1960. All the antelope on this reserve except gemsbok, feed by nibbling the plants here and there, and it was a tedious task to trace the exact feeding spot.

Experiments in Immobilising Ungulate Mammals

The technique of immobilising wild mammals by injecting them with drugs has received more attention in East Africa than in other parts of the continent. The present author became interested in immobilisation as a means of capturing springbok Antidorcas marsupialis which were to be marked and released for life history studies. Advantage was taken of opportunities to experiment on other species and the results of this work are presented here.