This image is one of a masked booby flying by low over the beach, the sound it makes is just like that made by a glider when it passes overhead. The MP3 you are listening to is the sound made by the same species of bird in passing overhead in a different mode; a high speed stoop, wings closed, legs tucked up and gliding on a steep slope at extremely high speed for the island. In the late afternoon after a day of fishing offshore the boobies return to Raine Island to their nests and as they near the island encounter the airborne thieves, frigate birds which harass the boobies until they regurgitate their recently caught meals and acquire a free meal. The boobies avoid this by flying to great heights as they near the island and then diving at great speed through the frigate gauntlet just off the beach. I tried to photograph the behavior but the birds just looked like a blurry speck in the sky with nothing around to give scale. It is very dramatic as they pass overhead. Only the masked boobies appear to have learned this behavior.

Sound recording by Ashton Ward. ashton@wildbluemusic.com