Hummingbird Diversity
Hummingbirds belong to an extremely diverse group of birds, with more than 330 species and 100 genera. All hummingbirds feed on nectar, so their diversity illustrates the many different relationships that these birds have evolved alongside the plants on which they feed as well as the diversity of habitats they have colonized. They inhabit humid tropical forests, pine forests, arid deserts, deciduous forests, arid scrub, desert oasis, coastal lowland, and alpine tundra.
Evolutionary History
Hummingbirds are poorly-represented in the fossil record and as a result scientists have long relied on hummingbird anatomy and appearance to form classification hierarchies. Hummingbirds are usually classified in the order Apodiformes which also includes tree swifts and true swifts, though there has been some debate that they should be placed in a group by themselves.
Hermits and Non-Hermits
The hummingbird family is subdivided into two groups, the hermit hummingbirds (Subfamily Phaethornithinae) and the trochilines (Subfamily Trochilinae).