The smallest birds species hummingbird; Anna’s hummingbird is popularly known as Color Changing Bird
Hummingbirds are all very small birds, and many are minute. Even the largest (Patagonia gigas) of western South America, is only about 20 cm (8 inches) long, with a body weight of about 20 g (0.7 ounce), less than that of most sparrows. The smallest species, the bee hummingbird (Melllisuga) sometimes, Calypte (helenaee) of Cuba and the Isle of Pines, measures slightly more than 5.5 cm, of which the bill and tail make up about half. Weighing about 2 g, this species is the smallest living bird and ranks with the pygmy shrews as the smallest of warm-blooded vertebrates.
The structure of the hummingbird makes full use of light waves and wavelengths to change color. Their iridescent feathers have layers of air bubbles at the surface which means that the light doesn’t just hit the surface and stay there, as it would with normal feathers.
The brilliant, glittering colors in the feathers (usually of the males only) change into metallic bronze, dark green, copper red, reddish-brown, metallic green, and rose red.
