Giraffes are semi-gregarious animals that live in loose herds often under the leadership of a male. The groups are made up of about 7 or 8 individuals, or a group of single bulls. The giraffe herd is informal, and members of the herd may be scattered over a considerable distance, rejoining the herd at will. There are no firm bonds among the individuals, who appear to come and go as they please. Concentrations of around 50 giraffes are common in some locations. This, though, has nothing to do with social ties, and occurs only because that area has an abundance of their favoured foods.

Giraffe herds are often found in association with zebras, impalas, ostriches or wildebeests. The giraffe herd is easily startled, and although they are a popular prey of lions, they can fight back well, delivering incredible blows to the lion┐s forelegs. Predators have been known to come off second-best against the giraffe. Fighting among the giraffe bulls themselves is not uncommon. They strike alternately against each other with their heads. Giraffes use the skull like a club when fighting and the skin is enlarged into a thick dermal armour to counter any blows received. The giraffe┐s skull is very heavy and can be quite a weapon, but injuries are rare because the male┐s horns are blunt and covered with skin.

While the younger bulls often associate loosely, travelling together, the older bulls are more solitary. The large, old bulls are very dominant and spend a lot of time searching for females that are ready to mate. A dominant bull will approach a herd, draw himself up to full height, and stare at a potential rival. The weaker bull will usually leave, but some do not and this is when the fights occur.

Although they are able to fight successfully against a predator, giraffes are vulnerable when they are drinking and sleeping. The giraffe┐s head does not reach the water so it must spread its legs in an awkward position to lower its neck. They cannot get out of this position fast enough should a lion leap out while they are drinking. Water holes are therefore dangerous places for giraffes, and usually one giraffe remains on the lookout while others drink.

Sleeping is also a dangerous time, because once the giraffe is lying down, it is difficult to stand up quickly. It is a lengthy effort involving swinging of the neck and kneeling before standing. Again one giraffe will usually stand watch while the others sleep. At other times, the giraffe naps standing up, leaving one eye open and alert.

Diet

The giraffe is a browser. It feeds on leaves of selected species of about 100 different varieties including Acacia and Mimosa. Acacia is the giraffe┐s favourite food because it contains all the nutrients it needs and its leaves are up to 75% water. Interestingly, male and female giraffes often browse in different areas. The males usually browse in wooded areas, and the females and their babies in open spaces.

Herbivorous animals like the giraffe must eat for most of the day to obtain sufficient nourishment, often eating for 15-20 hours per day. They browse for several hours after dawn and at dusk, and save the middle of the day for chewing their cud. The tongue is the giraffe┐s most important feeding aid and it may be over 45 centimetres long. The tongue is used to grasp branches and then the canine teeth are used in a comb-like action to strip the leaves off the branch.

Giraffes are ruminants and, like cows, possess a four-chambered stomach that is filled with plant digesting bacteria. They eat quickly, barely chewing their food the first time around. They then regurgitate their food, re-chew it and re-cover it with salivary enzymes. The dew on the leaves enables giraffes to go for many days without drinking. Because they feed on the leaves of trees, and can reach the tops of the trees, giraffes have a year-round food supply. They are not affected by seasonal variation and are therefore very successful foliage feeders.

Adaptations

Because of the length of the giraffe┐s neck and the height of the head above the heart, the blood vessels have evolved special valves to ensure that the blood reaches the brain, and to prevent the blood rushing to their head when they lower it to drink. The long neck enables the giraffe to eat the tender, new leaves on the tops of trees, which are out of reach to other herbivores sharing the same country. This adaptation also keeps the giraffe in ranchers┐ good books because the giraffe does not compete with cattle for food. Land owners therefore happily let giraffes share their land. This has meant the giraffe has remained abundant in numbers and not shot like other animals.

The giraffe┐s height also provides them with a clear view of distant predators. The slit-like nostrils can be closed to prevent loss of moisture and the distinctive patchy colouration of the coat is an adaptation for camouflaging the animal in the open bushland savanna where it lives.