Food Consumption and Energy Budgets of the Giraffe
(1) To estimate the efficiency of the foraging strategy described in Pellew (1984), the rates of food intake of adult giraffe in the Serengeti National Park are assessed. Daily energy intakes derived from the diet are compared with estimates of the energy requirements for year-round reproduction. The reproductive performance of giraffe in the Serengeti is […]
Inducible defences in Acacia sieberiana in response to giraffe browsing
Acacia trees comprise a principal component of the diet of many African browsers. The resultant browsing pressure has led to the evolution of both physical and chemical responses in Acacia trees. In an observational study, we investigated the physical and chemical defenses in Acacia sieberiana var. woodii in response to different intensities of giraffe herbivory. […]
Browsing Lawns? Responses of Acacia Nigrescens to Ungulate Browsing in an African Savanna
We measured browsing-induced responses of Acacia trees to investigate ‘‘browsing lawns’’ as an analogy to grazing lawns in a semiarid eutrophic African savanna. During the two-year field study, we measured plant tolerance, resistance, and phenological traits, while comparing variation in leaf nitrogen and specific leaf area (SLA) across stands of Acacia nigrescens, Miller, that had […]
The feeding biology and potential impact of introduced giraffe (giraffa camelopardalis) in the Eastern Cape province, South Africa
Giraffe (Giraffa camelopardalis) are extralimital (non-native) to the Eastern Cape Province, South Africa yet they have and continue to be introduced to the region. Financial gain has arguably been the driving force behind these introductions as foreign tourists associate giraffe with Africa and the African wildlife experience. This raises a number of ethical, ecological and […]
Why do some African thorn trees (Acacia spp.) have a flat-top: a grazer-plant mutualism hypothesis?
The quintessential African savanna tree is the flat-topped Acacia. However, the reason for the architecture occurring in sparse-canopied small-leafed tree species from well-lit, often mesic, environments is unclear. Brown (1960) suggested that it reduced feeding by the distinctly African herbivore, the giraffe. Escaping recaptured herbivore and/or fire damage is crucial for palatable savanna trees such […]
Did the elephant and giraffe mediate change in the prevalence of palatable species in an East African Acacia woodland?
We report on a 2009 survey of Acacia woodlands in the Seronera area of central Serengeti, Tanzania, and compare the results to previous surveys from the 1970s–1980s. We document a substantial change in woodland structure and composition. From 1978 to 2009, woody plant density (mean ± SD) declined from 255 ± 35 trees ha−1 to 147 ± 14 […]
Seed dispersal of Acacia erioloba by African bush elephants in Hwange National Park, Zimbabwe
Approximately two-thirds (64%) of all dry season samples of elephant dung analysed during a 3-year study in the Main Camp subregion of Hwange National Park, Zimbabwe, contained seed and/or pod materials from Acacia erioloba. Most seeds were recovered intact and actively germinating seeds were not uncommon. Very little pod mass relative to seed mass was […]
Interactions between large African browsers and thorny Acacia on a wildlife ranch in Kenya
Some plants respond to browsing with compensatory regrowth of plant tissues and with increased thorn growth. Associations between browsers and their preferred forage were examined through wandering quarter vegetation sampling and observational studies in an effort to understand how some plants respond to browsing by large African herbivores. Acacia seyal (n = 2680) A. drepanolobium […]
Not all ants are equal: obligate acacia ants provide different levels of protection against mega-herbivores
In obligate ant–plant mutualisms, the asymmetric engagement of a single plant species with multiple ant species provides the opportunity for partners to vary in their behaviour. Variation in behaviour has implications for the interactions with third-party species such as herbivores. This study assessed the effect of obligate ant mutualists (Crematogaster mimosae, Crematogaster nigriceps and Tetraponera […]
Structure and composition of Acacia xanthophloea woodland in Lake Nakuru National Park, Kenya
The woody vegetation of Lake Nakuru National Park occurs along rivers, lakeshores and flood plains. Four different sites within the Acacia xanthophloea woodlands were selected for the study. Vegetation structure was not significantly different in the four woodlands used for the study, but these sites differed in the relative density of Acacia trees. Regeneration of […]