More about giraffes

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.