Large Quetal

This species is 36 to 40 cm (14–16 in) long, plus up to 65 cm (26 in) of tail streamer for the male, and weighs about 210 g (7.4 oz). It is the largest representative of the trogon order.^[6] The subspecies costaricensis is slightly smaller than the nominate race, with tail plumes that are both shorter and narrower.

Resplendent quetzals have a green body (showing iridescence from green-gold to blue-violet) and red breast. Depending on the light, quetzal feathers can shine in a variant of colors: green, cobalt, lime, yellow, to ultramarine.^[7] Their green upper tail coverts hide their tails and in breeding males are particularly splendid, being longer than the rest of the body. Though quetzal plumages appear green, they are actually brown due to the melanin pigment.^[8] The primary wing coverts are also unusually long and give a fringed appearance. The male has a helmet-like crest. The bill, which is partly covered by green filamentous feathers, is yellow in mature males and black in females. Their iridescent feathers, which causes them to appear shiny and green like the canopy leaves, are a camouflage adaptation to hide within the canopy during rainy weather.^[7]

The skin of the quetzal is very thin and easily torn, so it has evolved thick plumage to protect its skin.^{[citation needed]} Like other members of the trogon family, it has large eyes that adapt easily to the dim light of its forest home.^{[citation needed]}

The “song” is a treble syllable described as kyow or like “a whimpering pup”, often in pairs, which may be repeated monotonously. Resplendent quetzals have other unmusical calls as well.