With their stilt-like legs, incredibly long necks and dexterous, elongated tongues, giraffes (Giraffa camelopardalis) are able to feed on foliage that's out of reach to other herbivores. Despite this latitude in food choices, giraffes overwhelmingly prefer browsing on the shoots and leaves of trees and shrubs, particularly the very thorny Acacia species.
Unlike many of Africa’s large mammalian herbivores, which alternate between browsing and grazing, giraffes are almost exclusively browsers – feeding primarily on leaves and the protein-rich shoots of trees and shrubs. They will also eat herbs and vines, as well as fruits and flowers when available. Giraffes have occasionally been observed grazing on grasses in nutrient-poor environments, although the position required to reach the ground makes them more susceptible to predators. In most areas, trees and shrubs in the Acacia species – a cousin of mimosas – make up the bulk of their diet. Giraffes use their long, prehensile tongues to navigate through the trees’ thorny branches to find tender shoots and leaves. Thickened papillae along the tongue’s surface further protect the giraffe from thorns. With their unusual physique, giraffes can comfortably feed between 1.6 and 15 feet off the ground. The next tallest browser – the kudu – can only reach 6.5 feet.
Give the Giraffe a Bone
With respect to feeding ecology, male and female giraffes are not created equal. The males, 20 percent taller than the females, can feed at higher levels. Breeding females tend to consume more nutritionally rich foods, whereas bulls eat foods higher in fiber and lignin. In a 2003 study on the foraging preferences of giraffes in Niger, Lauren E. Caister and her colleagues of the State University of New York at Syracuse found that nursing cows avoided leaves high in tannin, even when it meant giving up higher-quality forage. To support the growth of their unique skeletons, giraffes require two to three times more calcium and phosphorous than other similar-sized mammals. Most of their calcium requirements are met through diet, but sources of sufficient phosphorous remain a mystery. In a 2008 study, University of Pretoria's I. P. Bredin and his colleagues hypothesized that giraffes may acquire phosphorous from eating bones, a behavior known as osteophagia, which is frequently observed in giraffes, particularly in the winter months when the nutrient quality of foliage falls.