The singing sounds that birds make, especially the musical calls they use to communicate with each other.
Compound of 'bird' (from Old English 'brid') and 'song' (from Old English 'sang'). The combination became a specific term for avian vocalizations, emphasizing the musical quality of their calls.
Birdsong is nature's original music—neuroscientists discovered that some birds actually learn their songs from their parents like human children learn language, and some birds create regional 'dialects.'
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