Giraffe

Giraffe

Of all Africa's wild animals, the giraffe is possibly the most distinctive, for there is no other animal at all similar on any other continent. It has only one living relative, the odd-looking okapi of the central African rain forest. The giraffe is the tallest member of the animal kingdom - males average 5.5 metres, females a little less.Their unique form is the result of some remarkable adaptations, and has enabled them to exploit a food niche not utilised by other herbivores - the leaves on the uppermost branches of trees.

Giraffe are selective in their choice, favouring various species of Acacia, Combretum, Commiphora, Terminalia, Balanites and Ziziphus - some of these plants have evolved chemical defences, however, and release unpalatable tannins when over-browsed. The bluish, prehensile tongue is able to wrap around even the thorniest of twigs to remove nutritious foliage.

Seven Sub-species

There are several distinct colour forms of giraffe, seven of which have been accorded sub-species status. The most distinctive is probably the reticulated giraffe of the semi-arid savannah of central Kenya and Somalia, which has an exquisite checkerboard coat. The southern giraffe occupies the area south of the Zambezi, while the similar Maasai giraffe occurs in Tanzania and southern Kenya.

Unique Blood-pressure Controls

Many scientists and casual observers have been intrigued by the blood-pressure regulations in an animal with so long a neck and legs. Research has shown that the giraffe has a very large heart (13kg) and that its pumping power is three times that of a man. Most important, there is an intricate network of valves in the veins and blood vessels of the neck, which prevents the brain from being filled or emptied of blood too quickly. One highly specialised vessel near the brain acts as a sponge, slowly absorbing blood to the point where pressure warns the animal to lift its head before damage occurs. Next time you see a giraffe drinking, notice that it never keeps its head down for too long.

Taller than the Trees

The word "giraffe" seems to have stemmed from the Arabic word "xirapha" meaning one who walks swiftly. The specific name Camelopardalis was apparently coined by the Greeks who, when first confronted with the creature, thought it a cross between a camel and a leopard! The Zulu call the giraffe "ndhlulamithi" - which means "taller than the trees". Their height affords them excellent visibility and antelope and zebra frequently associate with them for their ability to detect predators.

Social Habits and Predators

Giraffe have an unusual social system which has yet to be fully understood. Females live apart from males in home ranges of about 25 square kilometres. The males may be solitary, but just as often congregate in bachelor herds. Their large size is a deterrent to most predators, but lions are quite capable of toppling fully-grown adults and some prides actually prefer them as prey. A single calf is born and although mothers put up a stern defence against predators such a lion and hyena, less than a quarter of the young survive their first year.

The status of giraffe in Africa is currently quite secure, with healthy populations in most savannah parks and reserves. They do not survive outside of protected areas and have been successfully reintroduced in reserves such as Phinda Private Game Reserve and Madikwe Safari Lodge Game Reserve in South Africa.

Further Reading
Estes, R. D. 1991. The Behaviour Guide to African Mammals.
Russel Friedman Books, Halfway House.
Kingdon, J. 1997. Kingdon Field Guide to African Mammals. 
Academic Press, London.

Posted: Mammals by CC Africa, Date: 21 November 2006