When observed for a sufficient period, omnivory is clearly a combination of carnivory and herbivory. The proportions of animal and plant foods consumed by omnivorous mammals are dependent both upon species' preferences and foods available in the environment. Omnivorous species are found in taxonomic orders that include bats, marsupials, pigs, primates, rodents, and Carnivora.[1,2] However, grouping these species in an omnivorous category tends to obscure the diversity of their dietary habits. All are presumed to consume animal tissues of various types, but food selections from the plant kingdom are sometimes used to identify particular specializations. For example, bats that consume insects incidental to (or as supplements to) their principal food nectar may be called nectarivores. Primates feeding on insects and small vertebrates but predominantly on plant exudates may be known as gummivores. Rodents feeding on invertebrates and small vertebrates but mainly on seeds may be known as granivores. Although there seem to be no agreed-upon proportions of animal and plant foods that define a mammal as a facultative carnivore, facultative herbivore, or omnivore, it is presumed that if significant amounts of foods are chosen from both the animal and plant kingdoms, the previously mentioned specialized feeders can be classified as omnivores.[2-4] Other, less specialized consumers of animal and plant material (such as American black bears or maned wolves), are usually known simply as omnivores. The diets of American black bears (Ursus americanus) are commonly about 75% vegetable matter, such as berries, acorns, beechnuts, wild cherries, grass, herbs, and roots but also include insects, honey, carrion, and mammalian prey.[1,5] The diets of maned wolves (Chrysocyon brachyurus) vary appreciably in their proportions of vegetable and animal matter, depending upon location, but include small rodents, birds, armadillos, invertebrates, fruit (particularly Solanum lycocarpum), herbs, and grass.[1,6]
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