Because birds do not have a strong sense of smell they rely on vision and sound. Birds use sounds other than those created by their vocal chords. Birds also use their wings to create sounds, simply by clapping them together as the wood pigeon or by having modified feathers which vibrate at a set frequency when exposed. Other birds which make sounds with their wings include Mute Swans, Hummingbirds, and Bellbirds. Perhaps the best known of these percussive sounds is the drumming of woodpeckers. Each woodpecker, has its own drumming pattern so male and female birds can easily recognise each other while they are out foraging.
Birds also make other noises, like chip notes, for many reasons including: to hold a flock together in dense foliage or during nocturnal migrations, to intimidate and drive away enemies or competitors, to convey information about food or predators, and to serve as an identification "password".
Some songbirds are known for imitating the sounds of other birds and animals. Mockingbirds will even imitate machinery. European Starlings, Catbirds, and Thrashers are imitators. Blue Jays will imitate the call of a hawk. Perhaps the most unusual however is the Palm Cockatoo which makes drumsticks from twigs and beats them against a hollow log in time with a pirouette during courtship.
The Passerines have the most well-developed songs and calls, but other birds with less vocal abilities have developed other sounds. Kiwis stamp their feet when annoyed. Boat-billed Herons, Storks, and Albatrosses rattle or clap their bills. Woodpeckers drum. The Ruffed Grouse drums with its wings. The nighthawk and hummingbirds often make sounds with their wings or tails. A number of birds make whistling sounds as they fly through the air- may or may not serve a purpose.

Of course, not all birds sing. Vultures make no noise at all. Other birds, such as storks and pelicans, don't make much. Many birds make short, simple sounds known as calls. But only the birds known as passerines, or songbirds, actually sing. Among the 5,000 kinds of songbirds are many birds you may know, such as robins, sparrows, cardinals, blue jays, and even crows.

 
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