Just like human, many animals have the capability to communicate with each other and with other species. Different animals display a variety of forms of communication, ranging from gestures, facial expressions to vocalization and gaze following. These forms of communication are essential in animals' social behaviors, interactions and especially mating rituals. Bird vocalization, such as bird songs and bird calls, is the most obvious and popular form of communication among birds and has long interested human because of its melodiousness. It is the language of birds which can be used to identify bird species and is also a form of animals' sexual selection and territorial establishment. Bird calling can travel a great distance and thus can attract the opposite sex and defend a territory in a wide area
Loons, a group of aquatic birds - most popular in North America, also communicate with each other by a very beautiful and unique song. Like other birds, loons produce songs to gain contact, signal alarm or worry and to mark territories.
"Common Loon singing"
Besides birds, whales, especially humpback whales, are among few marine animals that produce melodic sound, known as whale song, to communicate with each others. Depending on male species, these sounds can be extremely loud. Many marine biologists have described the songs as "probably the most complex in the animal world".
"Migaloo the White Whale Speaks"