Bird songs may sound like whimsical fun to humans, but for birds, it is a complex system with key functions. The primary purpose of bird vocalization is to attract mates. The second main purpose of bird calls and songs is territory defense.
Territorial birds such as jays, ravens, robins, and swifts use birdsong to establish territorial boundaries. Birdsong and calls are even used to communicate across species. For example, birds will use mobbing calls to “recruit” nearby birds to band together and help drive out predators such as owls or eagles.
Check out the following infographic, courtesy of AAAStateofPlay.com, to discover 50 bird species and the sounds they make.