White-necked Jacobin (Florisuga mellivora mellivora) female

23 January 2009, Rancho Naturalista, Costa Rica This is a female with an interesting patchwork of blue and green plumage. Females of this species are highly variable with some individuals almost indistinguishable from adult males. Females average slightly smaller than males and have slightly longer bills. We usually think of the brightly colored male plumage as derived, having evolved through sexual selection in which males compete for females by showing off. However, in hummingbirds, it seems the bright male-like plumage may be the ancestral state and the duller female plumage derived from it as a predator avoidance adaptation. Evidence for this comes from the Lesser Antilles where bird-eating raptors are rare or absent. There hummingbirds tend to be monomorphic with females similar to or indistinguishable from the glittering males. Panasonic Lumix LZ5 / Nikon FieldScope 3 / 30X WA hand-held (no adapter)