humpback serenade

Singing whales like a big audience
NewScientist.com 27 May 2007

Sing and attract females, or keep quiet and eat? It's a tricky dilemma for a male, to be sure, but one that humpback whales must wrestle with as they migrate to their summer feeding grounds. Males that sing swim more slowly than those that don't, possibly ending up with less time in the feeding grounds to fatten up for the next winter. On the other hand, singers may attract more mates. Michael Noad and colleagues at the University of Sydney in Australia tracked a population of humpback whales during the annual migration from low-latitude breeding areas to Antarctic feeding grounds. Using hydrophones to capture their song along with land-based observations, they calculated the swimming speed and singing status of each whale. While non-singing whales averaged 4 kilometres per hour, singers - which are always male - moseyed along at only 2.5 km/h (Marine Mammal Science, DOI: 10.1111/j.1748-7692.2007.02414.x). A few singers were clocked at around 15 km/h, showing that it's not impossible to sing and swim fast. So why slow down? It could be a strategy to squeeze a bit more breeding into the season. Slowing down lets the singer be heard by a procession of passing females. "It effectively gives them a larger audience," says Noad.