Some might say that despite their popularity, Thai dove-cooing contests, which have now been held for more than 30 years, have not received the academic attention they deserve. Either way, things changed with the 2005 (#9) edition of the journal MANUSYA:Journal of Humanities (a publication of Chulalongkorn University in Bangkok, Thailand) 
in which Professor Wanni Wibulswasdi Anderson [pictured] of the Department of Anthropology and Ethnic Studies, at Brown University, Rhode Island, US, presented a paper which covers the history of, the methodology of and the the sociological implications of the contests :‘Beyond the Cockfight: Masculinity and the Thai Dove-Cooing Contest’
“Doves in the contest are classified into 3 categories, based on the tonal characteristics of their cooing: low pitch, medium pitch, and high pitch. Each dove sings individualistic songs. The singing of each dove is listened to for one minute by two judges, each judge at a different interval. The melodic beauty of the cooing is evaluated and judged as a series of notes or movements: beginning movement, middle movement and end movement.”
Improbable has not been able to find up to date information on the contest, but here are the results of the 2006 competition.
BONUS (somewhat related) Pigeon Ping Pong competition – as implemented by the late professor Burrhus Frederic Skinner.