Bird vocalization includes both bird calls and bird songs. In non-specialized usage, bird songs are the sounds that are sweet to the human ear. In ornithology and birding, songs (moderately complex vocalizations) are distinguished by work from calls (generally simple vocalizations).
The distinction between songs and calls depends on multifaceted nature, length, and setting. Songs are longer and more perplexing and are related with romance and mating, while calls tend to serve such capacities as cautions or keeping individuals from a run in contact. Different authorities, for example, Howell and Webb (1995) make the distinction in light of capacity, with the goal that short vocalizations.