Cuba

Cuba is also home to the world's smallest bird, the Havana hummingbird (Mellisuga helenae).

An excerpt from the article 47 facts about Cuba
It is a small species of bird in the hummingbird family (Trochilidae). It is endemic to Cuba and to Isla de la Juventud. The body length of this hummingbird is about 6.3 cm, of which 1.2 cm is the bill, and 1.5 cm is the tail. The wing measures 2.9 cm, and the body weight is 1.6-1.9 g. The bright, iridescent colors of the plumage make the bird look like a little jewel. The International Union for Conservation of Nature (IUCN) classifies the Havana hummingbird as a near-threatened species because of the destruction and conversion of its habitat.