Male humpback whales change their songs when they hear other males singing along.
Like a songbird calling another out, one male humpback whale may make another change his tune.
Studying humpbacks with methods adapted from bird research has uncovered the first known instances of what look like whales responding musically to each other's songs, says Danielle Cholewiak, a researcher for the Stellwagen Bank National Marine Sanctuary based in Scituate, Mass.
Cholewiak and colleagues detected melodic adjustments when a solo singer encountered another singer nearby and when researchers played their song remixes for whales.
Male whales may be using music to tell another male, "Hey, I'm talking to you," Cholewiak reported Oct. 14 at the Society of Marine Mammology's biennial conference.
Cholewiak "showed short-term acoustic interactions between males -- that was the new thing," said Adam S. Frankel of Marine Acoustics Inc., an independent consulting firm in Arlington, Va.
Among humpback whales, only males boom out long strings of repeating phrases of hums and whups and chirps. The sounds can make a boat vibrate, said Salvatore Cerchio of the Wildlife Conservation Society in New York City, who worked with Cholewiak on the new study. Scientists use the word song to describe this patterned male vocalization, just as they do for elaborate bird serenades.