Birds
Birds are perhaps the best-known chirpers. Though all birds can chirp, some do so more frequently than others. Sparrows, crows and bluejays are particularly loud chirpers, especially during breeding season. The chirps of birds serve a variety of functions, including marking territory and attracting mates.
Monkeys
Several species of monkeys chirp, most notably capuchin monkeys, which exhibit several distinct chirps. Numerous primatologists, including Karen B. Strier, have noted that these monkeys change the sound of their chirps depending on the message they are conveying to other monkeys. For example, alarm chirps differ when the capuchin is chirping in response to a bird instead of a snake. These chirps may be a way of conveying a specific message to other monkeys about where and how to hide from danger.
Rodents
Many rodents, including squirrels, chipmunks and chinchillas, chirp. Chinchillas exhibit a high, squeaky chirp in response to loneliness and stress and a softer chirp as a sign of affection or satiation. Squirrels and chipmunks most frequently chirp when playing and fighting.
Insects
Numerous species of insects chirp, including crickets and cicadas. Only male crickets chirp, leading entomologists to conclude that chirping is a mating behavior. The chirps of cicadas are actually three separate sounds that are so short and closely-spaced that they sound like one chirp.