Golden-crowned Emerald

The golden-crowned emerald (Cynanthus auriceps) is a species of hummingbird in the "emeralds", tribe Trochilini of subfamily Trochilinae. It is endemic to western Mexico. == Taxonomy and systematics == The golden-crowned emerald was originally described in genus Trochilus. Since then it has variously been classified as a subspecies of what is now Canivet's emerald (Cynanthus canivetii) and included in blue-tailed emerald (Chlorostilbon mellisugus). In 2020 the North American Classification Committee of the American Ornithological Society (AOS), the International Ornithological Committee (IOC), and the Clements taxonomy placed it in genus Cynanthus with Carnivet's emerald, broad-billed hummingbird (C. latirostris), Turquoise-crowned hummingbird (C. doubledayi), and the Cozumel emerald (C. forficatus). The 2020 Version 5 of BirdLife International's Handbook of the Birds of the World retains it in Chlorostilbon. The golden-crowned emerald is monotypic. == Description == The golden-crowned emerald is 7.5 to 9.5 cm (3.0 to 3.7 in) long and weighs about 2.2 g (0.078 oz). The adult male's crown is brilliant golden green and the rest of its upperparts duller golden green to bronzy green. Its underparts transition from an almost pure green on the chin and throat to brilliant golden green at the vent. The tail is long and deeply forked…