Cuba's Bee Hummingbird, a species endemic to the country (and rare), is the world's smallest bird, and the smallest warm-blooded vertebrate.
Bee Hummingbird, Cuba (Above)
The adult Bee Hummingbird weighs approximately 0.06 ounces, which is about the same as a paperclip, and is around 2 inches in length, as measured from beak to tail.
Bee Hummingbird, Cuba (Above)
For comparison, the other hummingbird commonly found in Cuba is the Cuban Emerald, which is more than twice its size. Along with the Bee Hummingbird, it's known locally as a "zunzún". In his "Field Guide to Birds of the West Indies", the ornithologist James Bond, for whom Ian Fleming named his secret agent no less, mentions that the Cuban Emerald is sometimes called the "God Bird" or "Zumbador". Personally, I prefer the onomatopoeia of the name "zunzún", which most closely captures the sensation of these acrobatic aviators zipping by your head (did I mention that I also like alliteration?)
Cuban Emerald, Cuba (Above)
I've included a photo of the Vervain Hummingbird from Jamaica, in case you were wondering who holds the title for the second smallest bird in the world. I also embedded the video of a Ruby-throated Hummingbird feeding on my deck a few summers ago (see below), just because.
Vervain Hummingbird, Jamaica (Above)
GoPro video of a female Ruby-throated Hummingbird at a feeder, Mid-Atlantic, U.S.A. (Above)
(Photos Copyright © Chad Fahs)