Unlike most other birds, hummingbirds bills have a pronounced overlap, with the upper bill curving around and over the sides of the smaller lower bill. When hummingbirds feed, the bill is usually only opened slightly, allowing the bill-shaped tongue to dart out and into the interior of flowers. The bill is rarely opened wide and in any case is limited in how far it can be opened, but is used for variety of tasks, including catching insects in flight, preeming feathers, carrying nesting material, constructing nests, feeding baby hummingbirds and attacking rivals. A few of the good ones for the study of Hummingbirds. Largest brain, relative to size, of all birds.
Hummingbirds have proportionally the largest hearts of any living animal.
Resting heartbeat is 480 beats per minute and can go as high as 1,260 per second when excited. Resting hummingbirds breathe 250 times a minute. Hummingbird feathers have two different ways of producing color. This reflective feature is what causes a hummer's gorget to glitter when you are looking at the bird headon and to become duller when seeing the same bird from another angle. Curiously, the pigment of hummingbird feathers does not include red or yellow.