Hummingbird
Hummingbirds are birds native to the Americas and constitute the biological family Trochilidae. They are among the smallest of birds, most species measuring in length. Indeed, the smallest extant bird species is a hummingbird, the bee hummingbird weighing less than .
Least weasel
The least weasel ("Mustela nivalis"), common weasel, or simply weasel in the UK and much of the world, is the smallest member of the genus "Mustela," family Mustelidae and order Carnivora. It is native to Eurasia, North America and North Africa, and has been introduced to New Zealand, Australia, Malta, Crete, Bermuda, Madeira Island, the Azores, the Canary Islands, São Tomé, the Falkland Islands, Argentina and Chile. It is classified as least concern by the IUCN, due to its wide distribution and large population throughout the Northern Hemisphere.