From Dr. George West, HMN co-founder and co-author of "Do Hummingbirds Hum?: Fascinating Answers to Questions about Hummingbirds" with Carol A. Butler
The smaller species have the most rapid wing beat of all birds (up to 200 beats per second during courtship, and regularly up to 80 wing beats per second in forward flight. They are among the fastest fliers of small birds: 50 - 60 kilometers per hour (30 – 37 miles per hour) in forward flight to 95 kph (60 mph) in dives.
Their ratio of heart size to body size is the largest of all warm blooded animals, and their heart rate ranges from 300 to over 1,200 beats per minute.
They have the relatively largest breast muscles of all birds (up to 30% of total body weight), and are the only birds whose upstroke provides as much power as the downstroke.
Hummingbirds include the smallest of warm-blooded vertebrates and have the greatest relative energy output of any warm-blooded animal.
Hummingbirds are found only in the Western Hemisphere.
They are the largest non-passerine family of birds, and the second largest family of Western Hemisphere birds in number of living species (about 335).
The inner wing bone (humerus) is short and heavy but the outer wing bones (manus or hand) are long. There are only about 5 secondary feathers on the inner wing and 10 primary feathers on the outer wing.
They have only 10 tail feathers while passerines have 12.
Their plumage is among the most densely distributed of all birds, and the feather structure is among the most specialized; but they have the fewest total feathers of all birds (often less than 1000).
They have a unique flight mechanism, capable of prolonged hovering and rapid backward flight.
They are the only birds that regularly become torpid at night, with a drop in body temperature of as much to as low as 19° C (65°F); however, their normal resting body temperature is among the highest (40°C = 108°F) of all birds.
Individual hummingbirds often consume more than half their total body weight in food and may drink up to eight times their weight in water and nectar each day.
Their brain size is among the relatively largest of all birds (up to at least 4.2% of total body weight).
Males play virtually no role in the reproductive process beyond fertilization.
Most species have limited vocal abilities, very few have true songs. Many of the identifiable sounds are created through feather vibrations.
Many hummingbird species have co evolved with particular flowering plants and their bill size and shape have developed to take advantage of their ability to feed on and pollinate particularly shaped flowers while hovering.
Where ranges overlap, some species hybridize. (We found 10 examples in Miller Canyon and 1 in Arivaca.) We do not know if the hybrids (F1 generation) are able to breed and produce F2 offspring.