Effects of body size on the diurnal activity budgets of African browsing ruminants
We compared the diurnal activity budgets of four syntopic species of African browsing ruminant that differ widely in body size. These were concurrently studied through all phases of the seasonal cycle, in the same area, using the same methods. We tested five predictions from the literature on how body size is expected to influence the […]
Evaluating Population Persistence of Censused and Unmanaged Herbivore Populations from the Kruger National Park, South Africa
The application of the Dennis et al. (Ecol. Monogr., 61, 1991) model to data from 12 herbivore populations from the Kruger National Park, South Africa, introduces “risk assessment’ procedures into the conservation management of free-ranging species. The model enables one to predict the probability of reaching an arbitrarily defined threshold population size using census figures […]
Giraffes and the pollination ecology of knobthorns (Acacia nigrescens)
Giraffes (Giraffa camelopardalis) consume large quantities of knobthorn (Acacia nigrescens) flowers every year, and may be acting as pollinators. Because knobthorns flower in the late dry season, nutritionally a critical time of year for ungulates, the flowers are an important source of food for giraffes, especially since they are not physically protected against herbivory. Giraffes […]
Are giraffes pollinators or flower predators of Acacia nigrescens in Kruger National Park, South Africa?
We examined the relationship between giraffes (Giraffa camelopardalis) and Acacia nigrescens in Kruger National Park, South Africa, to determine whether these tall ungulates may be providing a pollination service for the trees, or are simply flower predators. We quantified florivory and subsequent fruit set in the presence and absence of giraffes. Acacia nigrescens flowers are […]
Comparative changes in adult vs. juvenile survival affecting population trends of African ungulates
Among large mammalian herbivores, juvenile survival tends to vary widely and may thus have a greater influence on population dynamics than the relatively constant survival rates typical of adults. However, previous studies yielding stage-specific survival rates have been mostly on temperate zone ungulates and in environments lacking large predators. Annual censuses coupled with assessments of […]
Social influences on vigilance behaviour in giraffes, Giraffa camelopardalis
Vigilance in ungulates is considered to have a predominantly antipredator function, with the frequency and duration of scans per individual decreasing with increasing group size. Social influences on vigilance scans have been overlooked in studies on ungulates, although studies in primates and birds show that conspecific scans are important determinants of vigilance behaviour. We investigated […]
Browsing-induced Effects on Leaf Litter Quality and Decomposition in a Southern African Savanna
We investigated the linkages between leaf litter quality and decomposability in a savanna plant community dominated by palatable-spinescent tree species. We measured: (1) leaf litter decomposability across five woody species that differ in leaf chemistry; (2) mass decomposition, nitrogen (N); and carbon (C) dynamics in leaf litter of a staple browse species (Acacia nigrescens) as […]
Detection and characterisation of papillomavirus in skin lesions of giraffe and sable antelope in South Africa
Papillomavirus was detected electron microscopically in cutaneous fibropapillomas of a giraffe (Giraffa camelopardalis) and a sable antelope (Hippotragus niger). The virus particles measured 45 nm in diameter. Histopathologically, the lesions showed histopathological features similar to those of equine sarcoid as well as positive immunoperoxidase-staining of tissue sections for papillomavirus antigen. Polymerase chain reaction (PCR) detected […]
Oscillations in large mammal populations: are they related to predation or rainfall?
Cyclic population dynamics is relatively common among populations of small mammals in high latitudes but is not yet established among African savanna ungulates. However, oscillations may be expected in large mammal populations subject to quasi-periodic oscillations in regional rainfall. We evaluated evidence for environmentally entrained oscillations in a large-mammal predator–prey system in Kruger National Park […]
Condensed tannin as anti-defoliate agent against browsing by giraffe (Girafla camelopardalis) in the Kruger National Park
The feeding behaviour of giraffes in the Kruger National Park, South Africa, was observed over 12 months and the diet analysed for condensed tannin content. Supportive evidence was found for plant defence against excessive browsing by means of tannin biosynthesis. Condensed tannin negatively influenced acceptability and nutritional value of dietary browse to giraffes. The giraffes […]