GIRAFFE

Facts

Fully grown Giraffe stand 4.3–5.7 m (14–19 ft) tall, with males taller than females. The average weight is 1,192 kg (2,628 lb) for an adult male and 828 kg (1,825 lb) for an adult female. Despite its long neck and legs, its body is relatively short.  The skin is mostly grey or tan and can reach a thickness of 20 mm (0.79 in). The 80–100 cm (31–39 in) long tail ends in a long, dark tuft of hair and is used as a defence against insects.

The coat has dark blotches or patches, which can be orange, chestnut, brown, or nearly black, surrounded by light hair, usually white or cream coloured. Male Giraffe become darker as they grow old. The coat pattern has been claimed to serve as camouflage in the light and shade patterns of savannah woodlands. When standing among trees and bushes, they are hard to see at even a few metres distance. However, adult Giraffe move about to gain the best view of an approaching predator, relying on their size and ability to defend themselves rather than on camouflage, which may be more important for calves. Each Giraffe has a unique coat pattern. Calves inherit some coat pattern traits from their mothers, and variation in some spot traits is correlated with calf survival. The skin under the blotches may regulate the animal’s body temperature, being sites for complex blood vessel systems and large sweat glands. The fur may give the animal chemical defence, as its parasite repellents give it a characteristic scent. At least 11 main aromatic chemicals are in the fur, although indole and 3-methylindole are responsible for most of the smell. Because males have a stronger odour than females, it may also have a sexual function.

Both sexes have prominent horn-like structures called ossicones, which can reach 13.5 cm (5.3 in). They are formed from ossified cartilage, covered in skin, and fused to the Skull at the parietal bones. Being vascularised, the ossicones may have a role in thermoregulation and are used in combat between males. Appearance is a reliable guide to the sex or age of a Giraffe: the ossicones of females and young are thin and display tufts of hair on top, whereas those of adult males tend to be bald and knobbed on top. A lump, which is more prominent in males, emerges in the middle of the skull. Males develop calcium deposits that form bumps on their skulls as they age.

With eyes located on the sides of the head, the Giraffe has a broad visual field from its great height.  Compared to other ungulates, Giraffe vision is more binocular and the eyes are larger with a greater retinal surface area. Giraffe may see in colour  and their sense of hearing and smell are sharp. The ears are movable. The nostrils are slit-shaped, possibly to withstand blowing sand. The Giraffe tongue is about 45 cm (18 in) long. It is black, perhaps to protect against sunburn, and can grasp foliage and delicately pick off leaves. The upper lip is flexible and hairy to protect against sharp prickles. The upper jaw has a hard palate instead of front teeth. The molars and premolars are wide with low crowns on the surface.

The Giraffe has an extremely elongated neck, which can be up to 2.4 m (7 ft 10 in) in length. Along the neck is a mane made of short, erect hairs. The neck typically rests at an angle of 50–60 degrees, though juveniles are closer to 70 degrees. Each cervical vertebra is over 28 cm (11 in) long.  They comprise 52–54 per cent of the length of the Giraffe’s vertebral column, compared with the 27–33 percent typical of similar large ungulates, including the Giraffe’s closest living relative, the Okapi. The Giraffe head and neck are held up by large muscles and a niche ligament, which are anchored by long thoracic vertebrae spines, giving them a hump.

The front legs tend to be longer than the hind legs and males have proportionally longer front legs than females, which gives them better support when swinging their necks during fights. The hooves of large male Giraffe reach 31 cm × 23 cm (12.2 in × 9.1 in) in diameter.  The fetlock of the leg is low to the ground, allowing the hoof to better support the animal’s weight. A Giraffe has only two gaits, walking and galloping. Walking is done by moving the legs on one side of the body, then doing the same on the other side. When galloping, the hind legs move around the front legs before the latter move forward and the tail will curl up. The movements of the head and neck provide balance and control momentum while galloping. The Giraffe can reach a sprint speed of up to 60 km/h (37 mph) and can sustain 50 km/h (31 mph) for several kilometres.

A Giraffe rests by lying with its body on top of its folded legs. To lie down, the animal kneels on its front legs and then lowers the rest of its body. To get back up, it first gets on its front knees and positions its backside on top of its hind legs. It then pulls the backside upwards, and the front legs stand straight up again. At each stage, the animal swings its head for balance.  If the Giraffe wants to reach down to drink, it either spreads its front legs or bends its knees.

The Giraffe circulatory system has several adaptations to compensate for its great height. Its 11 kg (25 lb) and 60 cm (2 ft) heart must generate approximately double the blood pressure required for a human to maintain blood flow to the brain. As such, the wall of the heart can be as thick as 7.5 cm (3.0 in).

Giraffe browse on the twigs of trees, preferring those of the subfamily Acaciae and the genera Commiphora and Terminalia, which are important sources of calcium and protein to sustain the Giraffe growth rate. They also feed on shrubs, grass and fruit. A Giraffe eats around 34 kg (75 lb) of plant matter daily. When stressed, Giraffe may chew on large branches, stripping them of bark. Giraffe are also recorded touched on old bones.

During the wet season, food is abundant and Giraffe are more spread out, while during the dry season, they gather around the remaining evergreen trees and bushes. Mothers tend to feed in open areas, presumably to make it easier to detect predators, although this may reduce their feeding efficiency. As a ruminant, the Giraffe first chews its food, then swallows it for processing and then visibly passes the half-digested cud up the neck and back into the mouth to chew again. The Giraffe requires less food than many other herbivores because the foliage it eats has more concentrated nutrients and it has a more efficient digestive system.

The number of Giraffe in a group can range from one up to 66 individuals. Giraffe groups tend to be sex-segregated although mixed-sex groups made of adult females and young males also occur. Female groups may be matrilineally related. Generally, females are more selective than males when deciding which individuals of the same sex they associate with. Young males also form groups and will engage in play fights. However, as they get older, males become more solitary but may also associate in pairs or with female groups. Giraffe are not territorial but they have home ranges that vary according to rainfall and proximity to human settlements. Male Giraffe occasionally roam far from areas that they normally frequent.

Giraffe communicate using snorts, sneezes, coughs, snores, hisses, bursts, moans, grunts, growls and flute-like sounds. During courtship, males emit loud coughs. Females call their young by bellowing. Calves will emit bleats, mooing and mewing sounds. Snorting and hissing is associated with vigilance. During nighttime, Giraffe appear to hum to each other.

Reproduction in Giraffe is broadly polygamous: a few older males mate with the fertile females. Females can reproduce throughout the year and experience oestrus cycling approximately every 15 days. Female Giraffe in oestrus are dispersed over space and time, so reproductive adult males adopt a strategy of roaming among female groups to seek mating opportunities, with periodic hormone-induced rutting behaviour approximately every two weeks. Males prefer young adult females over juveniles and older adults.

Giraffe gestation lasts 400–460 days, after which a single calf is normally born, although twins occur on rare occasions. The mother gives birth standing up. The calf emerges head and front legs first, having broken through the foetal membranes, and falls to the ground, severing the umbilical cord. A newborn Giraffe is 1.7–2 m (5 ft 7 in – 6 ft 7 in) tall. Within a few hours of birth, the calf can run around and is almost indistinguishable from a one-week-old. However, for the first one to three weeks, it spends most of its time hiding, its coat pattern providing camouflage. The ossicones, which have lain flat in the womb, raise up in a few days. Mothers with calves will gather in nursery herds, moving or browsing together. Mothers in such a group may sometimes leave their calves with one female while they forage and drink elsewhere. This is known as a “calving pool”. Calves are at risk of predation, and a mother Giraffe will stand over them and kick at an approaching predator. Calves first ruminate at four to six months and stop nursing at six to eight months. Young may not reach independence until they are 14 months old. Females are able to reproduce at four years of age, while spermatogenesis in males begins at three to four years of age. Males must wait until they are at least seven years old to gain the opportunity to mate.

Male Giraffe use their necks as weapons in combat, a behaviour known as “necking”. Necking is used to establish dominance, and males that win necking bouts have greater reproductive success. This behaviour occurs at low or high intensity. In low-intensity necking, the combatants rub and lean on each other. The male that can keep itself more upright wins the bout. In high-intensity necking, the combatants will spread their front legs and swing their necks at each other, attempting to land blows with their ossicones. A necking duel can last more than half an hour, depending on how well matched the combatants are. Although most fights do not lead to serious injury, there have been records of broken jaws, broken necks, and even deaths. After a duel, it is common for two male Giraffe to caress and court each other.

Giraffe have high adult survival probability and an unusually long lifespan compared to other ruminants, up to 38 years. Adult female survival is significantly correlated with the number of social associations. Because of their size, eyesight and powerful kicks, adult Giraffe are mostly safe from predation, with Lion being their only major threats. Calves are much more vulnerable than adults and are also preyed on by Leopard, Spotted Hyena and Wild Dog. A quarter to a half of Giraffe calves reach adulthood. Calf survival varies according to the season of birth, with calves born during the dry season having higher survival rates.