Diversification of feeding strategies within each of the 19 chiropteran families (Hoofer and Van Den Bussche, 2003; Van Den Bussche and Hoofer, 2004; Simmons, 2005) typically is limited to one (13 families) or two (five families) food sources. The family Phyllostomidae, however, represents an exception to this pattern with six distinct feeding strategies: sanguivory, insectivory, frugivory, nectivory, carnivory (feeding on vertebrates) and omnivory.
Among families of bats, phyllostomids comprise the largest number of genera (56) and the third largest number of species (160+) (Simmons, 2005). They are distributed throughout tropical and subtropical regions of North and South America and have been highly successful in exploiting a diverse array of life-history strategies. Included among its members are three species of obligate sanguivores, a feeding strategy unknown in vertebrates other than fish (Figure 11.1). Among phyllostomids additional examples of feeding specialization exist, including subsisting exclusively on insects, as well as primarily on fruit, nectar, frogs, rodents and other vertebrates. Such specializations are remarkable when viewed in the context of the concomitant suite of adaptations associated with the sensory apparatus, locomotion, digestion, dentition, kidney function and reproduction, among others (Griffiths, 1982; Greenhall and Schmidt, 1988: Fleming et al., 2005) that must be favored by directional natural selection for successful exploitation of new ecological opportunities. No other clade of mammals with roots in the Eocene displays such radical evolutionary modifications.