By Laura Poppick, Staff Writer | April 03, 2014 12:05pm ET
Hummingbirds have evolved into hundreds of different species very rapidly over the past 22 million years, according to a study that presents the first-ever comprehensive hummingbird evolutionary tree.
A total of 338 hummingbird species are known to flutter the world today in a wide variety of environments, including highly inhospitable mountaintops with low oxygen levels. Researchers were interested in studying how these birds evolved to inhabit these harsh environments, but they needed a concrete family tree to do so. Such a tree had not yet been developed, so a team of researchers worked for about a decade to compile one using information from fossils, museum specimens and living species.
The new evolutionary tree, or phylogeny, shows that hummingbirds began splitting off from ancestral swifts and tree swifts roughly 42 million years ago, likely in Eurasia. The first evidence of the common ancestor of all modern hummingbirds appears much later, about 22 million years ago, in South America. Given the frequent feedingschedule the birds rely on to keep their wings flapping so quickly, researchers think the birds entered South America by way of North America, feeding along the way, rather than flying over the ocean.