Wildlife management in the Karoo

Wildlife management in the Karoo

The Karoo consists of a bewildering variety of physiographic landscape types, each of which contains a great diversity of habitats. This habitat variability is the foundation for a rich Karoo fauna diversity, for even within the seemingly vast and featureless plains there are escarpments, watered valleys with thickets, koppies and gorges. Seasonal rivers and streams support dense thickets of hardy trees, while mountain ranges, dolerite koppies and granite outcrops support a great diversity of shrubs, succulents, and grasses. The hot, dry plains support an arid-adapted vegetation cover of dwarf shrubs, succulents, seasonal grasses, and annual plants. In addition to these typical Karoo habitats are integrated mosaics of Karoo with Fynbos, Renosterveld, Subtropical Thicket, Grassland and Savannah which occur at the edges of the Karoo biome, and which further increase habitat variability.

As the Karoo landscape developed, a suite of ungulate species became adapted to each of the major Karoo habitat types. Some of these ungulates are ubiquitous Karoo generalists which once occurred widely across most of the biome. These are the eland, red hartebeest, springbok, common duiker, and steenbok. Other species have preferences for more specific habitat conditions, for example, the Cape-mountain zebra, mountain reedbuck, grey rhebok and klipspringer which occur in mountainous and broken habitats. Another habitat specialist group were the animals which favoured the grassy Karroid plains. These were warthog, black wildebeest, gemsbok, blesbok and quagga (which is now extinct). The network of wooded kloofs, valleys and seasonal river channels that bisect much of the Karoo provided habitat for specialist woodland browsers such as the black rhinoceros and kudu. Permanent rivers supported hippopotamus and migrant herds of elephant and buffalo.

The Karoo thus did once have an historical fauna consisting of suitably arid-adapted species. Introductions into game farms, game ranches and nature reserves should thus be partly based on this historical occurrence, as it has been repeatedly shown that these species have the best chances for long-term survival and productivity under the harsh Karoo conditions, whereas species from other regions do not adapt as well, particularly to the periods of prolonged drought.

Ungulate introductions, however, must be based on more than just historical occurrence. Although rich in a diversity of habitat types, much of the Karoo landscape has been impacted, and often severely degraded, by 300 years of livestock farming which resulted in overgrazing, trampling and soil erosion by wind and water. The evaluation of habitat condition in the Karoo is thus as critically fundamental as the determination of habitat types.

Within each of the major habitat types, the ungulates can be grouped according to their feeding habits. For example, kudu and common duiker are browsers that utilize the leaves and fruits of shrubs, red hartebeest, gemsbok, and black wildebeest are grazers and eland and springbok are mixed feeders which utilize both grazing and browse. Matching these herbivores to the Karoo habitat thus necessitates a careful evaluation of the availability of suitable and sustainable forage for each feeding type. Decisions to introduce ungulates must, therefore, be based on a careful evaluation of the quality and amount of suitable forage and the long-term sustainability of this forage within each of the habitat types.

The evaluation of habitat in any part of the Karoo will reveal that the vegetation consists of trees, woody shrubs, and dwarf shrubs (browse component) and grasses, herbaceous plants, and annual plants (grazing component). The ratio of browse to grazing differs from one area to the next and this means that the ratio of feeding types will also differ from one area to the next. In Savanna regions, a ratio of 40% bulk grazers, 20% concentrate grazers, 20% mixed feeders and 20% browsers is generally recommended. In the Karoo, however, the ratio of grazers: mixed feeders: browsers are more variable because of higher habitat variability, both spatially and temporally, and no standard ratio can be recommended for the Karoo areas. in practice, the situation in the Karoo often favours mixed feeders and browsers over grazers. Conditions in the Karoo closely follow the rainfall, and, in some areas, grassiness increases with good early and late summer rainfall while the failure of timely rains may result in the almost complete lack of any grass productivity at all. Grazing Karoo ungulates deal with this situation by simply switching from a largely grass diet to a Karroid dwarf shrub diet. Cape mountain zebra, black wildebeest and red hartebeest are particularly adept in this regard. Stochastic and unreliable rainfall thus has an important influence on the grazing:browsing ratio and consecutive years seldom experience exactly the same conditions. The ratio of grazers:mixed feeders:browsers for the Karoo areas must thus be specifically determined for each specific area of wildlife introduction.

The size of any game farm or nature reserve area and the ratio of browsing to grazing habitat types contained in it will be a much better indication of a suitable grazer:browser ratio for the ungulates on the area and it can be expected that this ratio will change significantly across the landscape with habitat variability. The condition of the habitat is also important for the determination of grazer:browser ratio because historical over-utilization with domestic livestock may have favoured the proliferation of unpalatable plant species. The careful evaluation of the condition of Karoo veld dominated, for example, by dwarf shrubs is critical because not all dwarf shrubs are equally palatable to all ungulates.The full article is for subscribed members only. To view the full article please subscribe. It’s FREE!Log In Register

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