Recent research has revealed that the lower the pitch of a male purple-crowned fairy wren, the larger the bird. In a study led by Dr. Michelle Hall of the University of Melbourne, scientists show for the first time that a bird's song is indicative of its body size. Similar evidence linking the pitch of an animal's call to its body size was previously established in frogs, but never before have scientists measured this phenomenon in birds.
Dr. Hall and her collegues measured the leg length of 45 adult male purple-crowned fairy wrens and then measured the pitches of their songs. They found a close correlation between the lowest song pitches and the largest birds.
Purple-crowned fairy wrens live in dense vegetation near creeks and streams in northern Australia. They have a light brown upper body, cream belly, and a blue tail. Males have a bright purple and black crown during the breeding season.
Photo © Michell Hall / University of Melbourne.