Smallest organisms
With a mass of approximately and a length of 5 centimetres (2.0 in), the bee hummingbird ("Mellisuga helenae") is the world's smallest bird species and the smallest warm-blooded vertebrate. Called the "zunzún" in its native habitat on Cuba, it is lighter than a Canadian or U.S. penny. It is said that it is "more apt to be mistaken for a bee than a bird". The bee hummingbird eats half its total body mass and drinks eight times its total body mass each day. Its nest is 3 cm across.
Fan-tailed raven
The fan-tailed raven ("Corvus rhipidurus") is a passerine bird of the crow family native to Eastern Africa and the Arabian Peninsula. Like the Forest raven, Little raven, Australian raven and Chihuahuan raven, it is one of the smaller raven species. The larger species of raven are the Common raven, Thick-billed raven, White-necked raven and Brown-necked raven with the Common and Thick-billed ravens being the world's largest raven species and the Little and Fan-tailed ravens being the smallest, in fact it is about the same size or slightly larger than the carrion crow (47–51 cm) but with a much thicker bill, shorter tail and much larger wings.