Hint: Birds are a group of Aves-class warm-blooded vertebrates characterized by feathers, toothless beaked jaws, hard-shelled laying of eggs, a high metabolic rate, a four-chambered heart and a solid but light skeleton.
The title of the smallest bird in the world goes to the bee hummingbird, which can be just 5 cm tall. At less than 2 grams, it is also the world's lightest bird, and has the world's smallest nest, made of cobwebs and lichen, where it lays eggs the size of peas.
Females are 2.6 g (0.092 oz) in weight and 6.1 cm (2.4 in) in length, marginally larger than males, with a mean weight of 1.95 g (0.069 oz) and 5.5 cm in length (2.2 in). It is, like all hummingbirds, a swift, powerful flyer.
There is a green pileum and a bright red throat in the male, iridescent gored by elongated lateral plumes, bluish upper parts, and mostly greyish white in the rest of the underparts.
The bee hummingbird appears rounded and plump compared to other small hummingbirds, which also have a slim appearance.
Female bee hummingbirds have a light gray underside and are bluish green. There are white spots on the ends of their tail feathers. Males have a reddish to pink head, chin and throat throughout the mating season. Just two eggs at a time are laid by the female, each about the size of a coffee bean.
The brilliant, iridescent colors of the feathers of the bee hummingbird make the bird look like a tiny gem. The iridescence is not always apparent, because it depends on the angle of view. The slender, pointed bill of the bird is adapted for deep probing into flowers.
By moving its tongue quickly in and out of its mouth, the bee hummingbird feeds mainly on nectar. In the feeding process, the bird picks up pollen on its bill and head. It moves the pollen as it flies from flower to flower. It plays an important role in plant reproduction in this way. The bee hummingbird can visit 1,500 flowers in one day.They are native to Cuba.
Note: The Bee Hummingbird's tiny wings were beating 80 times a second in flight. And they punch up to 200 times a second during a courtship ride! The whole head and throat of the male shine in fiery pinkish-red, and flaming red feathers point down the sides of the breast like spikes.