Peruvian Sheartail

Thaumastura cora can reach a length of about 13 to 15 cm (5.1 to 5.9 in) in males (tail 7 cm), of about 7 to 7.5 cm (2.8 to 3.0 in) in females. These tiny hummingbirds have a greatly elongated tail streamers and a short and straight black bill. The basic color of the plumage is iridescent green, with a white or light gray belly and an iridescent rosy purple to turquoise throat. The weight of this species is reportedly 2 to 2.5 g (0.071 to 0.088 oz), with an average mass of approximately 2.2 g (0.078 oz), which makes it one of the lightest birds alive. It seems to be the lightest known birds species found in South America,some 11.5 thousand times lighter than the greater rhea, the heaviest extant South American bird. Although other extremely diminutive South American hummingbirds, i.e. woodstars from the genera Myrmia and Chaetocercus based upon their tiny total lengths, may rival the Peruvian sheartail in lightness but have no published weights.