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Giraffe

CONSERVATION STATUS : VULNERABLE
COMMON EXTINCT
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Classification:

Other Common Names: “Twiga” in Swahili
Order: Artiodactyla
Genus & Species: Giraffa camelopardalis
Family: Giraffidae

Status:

Listed as Vulnerable on the IUCN Red List.

Range

Patchy, non-continuous distribution in portions of Africa south of the Sahara. Not present in most of western, central, and far southern Africa.

Habitat:

Savanna, scrub, open acacia woodlands and subtropical and tropical grasslands with trees and bushes.

Activity:

Most active during early and late hours of the day. Also active during the night. Bouts of sleep during the day and night usually last no more than a couple of hours at a time. Sleep is usually shallow. Deeper sleep typically only lasts for 5-10 minutes at a time.

Size:

Tallest mammal. Adult males (bulls) up to 18 ft. tall and 4,225 lbs; females (cows) up to 15 ft. tall and 2,600 lbs.

Longevity:

In the wild, 15-20 years up to a maximum of 26 years. In captivity, up to a maximum of 40 years. Females live 25% longer than males.

Diet:

Browse (leaves & young shoots). Acacia spp. are favored, but many other species of trees and woody bushes are eaten. Eat mostly deciduous species during rainy season and evergreen species during dry season. Long, black, prehensile tongue used to rip up to 165 pounds of browse (including thorny Acacia leaves) from tall trees each day. No upper incisors or canines. Males and females tend to eat from different parts of a tree to ensure that the sexes do not compete for food. At the zoo, they are feed alfalfa hay and alfalfa pellets.

Description:

Tallest living animal with the longest neck among living species. (Like all mammals, it has only seven cervical/neck vertebrae.) High shoulders sloping down to hind quarters. Large, hoofed feet. Pelage is medium to reddish brown, broken into splotches by buff-colored borders. Each of the nine subspecies has a characteristic color and pattern. Individuals have unique markings. Short, stiff, brown mane and a long tuft of hair at the end of the tail. Single pair of horns (specific to giraffes) on males and females; some populations have additional knobs.

Reproduction:

Gestation lasts 14-15 months, and females normally produce one calf at a time and can have up to 12 calves in her lifetime. Females give birth standing up. Calves may be over six feet tall at birth. Newborns are able to stand within 20 minutes and will grow over 2 meters (about 6 ft) in their first year. Young are weaned at about 12 months and become completely independent in 1 to 3 years. Sexual maturity takes place at 3.5-4.5 years.

Ecology, Adaptations, Etc:

Giraffes are somewhat social and may form loose herds of up to 50 individuals that may be spread out over large distances.  Herds can be composed of any combination of males, females, young, and adults. There is no leader, and little coordination among individuals. The composition of individuals changes constantly, even within a 24 hour period.

Giraffes are often seen foraging with other species, such as zebras, antelope, and ostriches.  Giraffes may act as sentinels for other animals due to their height and ability to see danger from far away.  Oxpecker birds climb all over giraffes, picking off ticks and other parasites. Piapiacs and cattle egrets take advantage of insects that are stirred up in the wake of a walking giraffe.  Every step a giraffe takes is 15 feet long, and their footprints are 12 inches long and 9 inches wide.

The giraffe has one of the shortest sleep requirements of any mammal, which is between 10 minutes and two hours in a 24-hour period, averaging 1.9 hours per day.  They sleep standing up, occasionally resting their head on a branch.  However, giraffes will sometimes sit down on top of their folded legs.

Predator defenses for adult giraffes include: large size, good vision, fast running, and powerful kicking.   Calves are more vulnerable, and their primary defense is camouflage.  They also grow quickly, doubling in size, during their first few years, making them less vulnerable to predation.

Both male and female giraffes have horns, called “ossicones”, which are different from the horns found on other hoofed mammals.  Most horns project from the frontal bones of the skull, but giraffe horns start as cartilaginous bumps which grow and ossify (become bony) starting at the tip, eventually fusing to the cranium over the sutures between the frontal and parietal bones.

Giraffe horns are paired, short, unbranched, permanent bony processes that are covered with skin and hair.  Males have larger horns that end with hairless knobs.  Horns on females and juveniles have straight ends that are tufted with hair.  Horns are present at birth and fully developed at age 4.5 in males and age 7 in females.  In both males and females, the forehead area can become more heavily ossified forming an additional knob in front of the main horns.  The knob on the male may develop into what looks like a third horn, and bony grown may continue all over the front of the skull becoming much more dense than that of females.

Males use horns and heavily ossified skulls during aggressive encounters with one another.  They spar with each other by standing side by side and swinging their necks to thump their heads into the other male’s body like a club.  These fights can be quite gentle, or quite fierce, sometimes resulting in knocked-out giraffes.  Once dominance has been established, the two combatants often coexist peacefully.

Each time a giraffe picks up its neck it picks up 550 pounds.  Because of its long neck, one would expect blood to rush to the brain of a giraffe when it lowers its head to drink, or to drain away from the brain when the head is lifted back up. Either scenario could cause the animal to faint, so giraffes have special adaptations to prevent this from happening.  A giraffe has a large, strong heart (24 in. long and 25 lbs.) that produces twice the blood pressure seen in humans.  The heart can pump 16-20 gallons of blood per minute against gravity when the head is erect.  The neck vessels are equipped with numerous one-way valves that prevent blood from back flowing to the brain when the head is lowered, and muscle fibers surrounding the veins slow the flow of blood when the head is raised again.

Historically, giraffes were thought to be mute.  However, they do possess vocal chords and recent research shows that they can make a variety of sounds.  Although normally quiet, the following types of vocalizations have been reported:  alarm snorts, bleating by calves, bellows by females looking for their young, raucous coughing by males during courtship, moaning, snoring, hissing, and flutelike sounds.  Giraffes may also communicate using infrasound (low-frequency sounds below the range of human hearing).