browsers - GCF Resource Library

Woody vegetation change in response to browsing in Ithala Game Reserve, South Africa

The impact of elephant and other browsers may be magnified when they are restricted within small, fenced reserves. These reserves are becoming commonplace in southern Africa. The composition and structure of the woody vegetation of a portion of the 30 000 ha Ithala Game Reserve, South Africa, was monitored annually from 1992 to 2000. Woody species described a continuum from those that declined in abundance and were threatened with extirpation (e.g. Aloe marlothii, Acacia davyi ), through those that remained

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Natural history miscellany winning by a neck: Tall giraffes avoid competing with shorter browsers

With their vertically elongated body form, giraffes generally feed above the level of other browsers within the savanna browsing guild, despite having access to foliage at lower levels. They ingest more leaf mass per bite when foraging high in the tree, perhaps because smaller, more selective browsers deplete shoots at lower levels or because trees differentially allocate resources to promote shoot growth in the upper canopy. We erected exclosures around individual Acacia nigrescens trees in the greater Kruger ecosystem, South

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The use of dosed and herbage n-Alkanes as markers for the determination of digestive strategies of captive giraffes (giraffa camelopardalis)

Selected aspects of digestion in captive giraffes were investigated in two trials with a type of marker that is new for digestive studies in non-domestic species. n-Alkanes were used as internal and external markers. In Trial 1, diet composition, intake, and digestibility were directly measured and estimated with the marker. Six giraffes were dosed once daily for 3 weeks with labeled pellets containing 3,800 ppm of each C28, C32, and C36 alkanes at ~100 mg/100 kg bodyweight. Intake of cabbage,

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Shoot characteristics of Acacia tortilis (Forsk.) in wildlife and rangeland habitats of Botswana

Length, branch production, orientation, spinescence and biomass were measured for current shoots of Acacia tortilis shrubs in a range of habitats in Botswana. All shoot characteristics varied between individuals and between habitats with longer, less spinescent shoots produced in the habitat recently protected from wildlife. Biomass allocated to woody material increased with shoot length at the expense of leaf mass, whilst investment in straight prickles was as much as 6% of shoot dry mass. Shoot length had significant effects on

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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 as acacias. The impact of fire depends on the fire intensity (mainly due to under-canopy dead grass biomass and weather conditions) and on woody plant

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Behaviour and the effect of giraffe on flora

The study has taken place in Etosha National Park whereby the behaviour and effect of giraffe on the flora was considered. The population of Etosha giraffe is a about 1800, which is high in the presence of other browsers. A lot of trees are pressurized by giraffe and a lot of individual tree spp are uprooted by elephants. The giraffe move from one place to another looking for food. The animals reconnaissance the area before they approach the waterhole. Much

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Feeding-height stratification among African browsing ruminants

This study investigated the hypothesis that the use of different feeding levels in the vegetation promotes resource partitioning among browsing ungulate species in African savannas. Focal animal feeding observations, recorded on a real-time basis using computerized data-capture system, were conducted on giraffe (Giraffa camelopardalis Linnaeus), kudu (Tragelaphus steosiceros Pallas), impala (Aepyceros melampus Lichtenstein) and steenbok (Raphicerus campestris Thunberg) in the central region of the Kruger National Park, South Africa, Although there was clear stratification in mean feeding heights among the

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Effects of resource limitation on habitat usage by the browser guild in Hluhluwe-iMfolozi Park, South Africa

Resource depletion and association increases in interspecific competition are likely to influence differential habitat usage amongst a guild. We tested some prominent theoretical concepts using observed differenced in seasonal habitat use amongst the savannah browser guild (elephant, giraffe, impala, kudu and nyala) in Hluhluwe-iMfolozi Park, South Africa. Herbivore locations (n= 3108) were recorded over 2 y using repeated road transects and, for elephant, GPS collars (187254 downloads). Densities were calculated using a novel GIS approach designed to be a cost-effective

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The maximum attainable body size of herbivorous mammals: morphophysiological constraints on foregut, and adaptations of hindgut fermenters

An oft-cited nutritional advantage of large body size is that larger animals have lower relative energy requirements and that, due to their increased gastrointestinal tract (GIT) capacity, they achieve longer ingesta passage rates, which allows them to use forage of lower quality. However, the fermentation of plant material cannot be optimized endlessly; there is a time when plant fibre is totally fermented, and another when energy losses due to methanogenic bacteria become punitive. Therefore, very large herbivores would need to

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Giraffe feeding on Acacia flowers: predation or pollination?

Consumption of flowers by the following four browsing ruminant species was monitored for two years in a southern African savannah: giraffe (Giraffa camelopardalis Linnaeus), kudu (Tragelaphus strepsiceros Pallas), impala (Aepyceros melampus Lichtenstein) and steenbok (Raphicerus campestris Thunberg). Flowers of Acacia nigrescens Oliver are an important food resource to giraffe in the late dry season. This is not necessarily deleterious to the reproductive potential of the plant however, as most or all African Acacia species bear high proportions of sterile flowers.

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