Evolutionary biologist Jim McGuire of the University of California, Berkeley, and his collaborators have found that although some hummingbird groups have saturated the available space in their environments, others are still developing into new species at an extraordinary rate. By comparing their rates of speciation and extinction, McGuire's team calculated that the number of hummingbird species could double before reaching an equilibrium in the next several million years.
_{Disponível em:. Acesso em: mar. 2014.}