Anyone who has seen a hummingbird poking her beak deep into a trumpet creeper blossom, or a honeyeater using its brush-tipped tongue to extract nectar from eucalyptus flowers, has witnessed something that, from a human perspective, is rather remarkable. Although many bird species avoid sugar-rich foods, others survive almost entirely on sugar-rich nectar or fruit, processing massive sugar loads without developing the diseases that such diets cause in people and other animals.