Which is the smallest bird in the world?

The smallest bird in the world is the Bee Hummingbird (Mellisuga Helena), which is found only in Cuba. Adult male Bee Hummingbirds can weigh less than 2.5 grams and measure about 2.25 inches (5.7 cm) long. Females are slightly larger, weighing up to 3 grams and measuring up to 2.75 inches (7 cm) long. These tiny birds are iridescent green and blue with a reddish-pink throat patch, and they are known for their fast wingbeats, which can exceed 80 beats per second.