There are two reasons why whales produce sounds; to communicate and to locate objects. Whales rumble, grunt, and gurgle using their voices to attract mates, communicate with offspring, and navigate through the ocean. Communication between humpback whales have been studied for nearly fifty years. One question remained a mystery, until now. Only male humpback whales sing intricate songs and it was first thought that these songs were to attract attention of females. However, no females have been viewed approaching a singing male.
Singing seems to be attracting attention from other males instead of females. When male humpback whales approach the singer, the singing ceases, the the two males go off silently together. Now using techniques that have been used in bird research, humpback whales have been found to be responding musically to each other's songs. Melodic adjustments were detected when a solo singer encountered a nearby singer. This demonstrated short term acoustic interactions between males.
Although observations have not helped scientists determine whether males use songs in the same way a birds. Playback experiments with female humpback whales were inconclusive and scientists still have yet to see this species mate. Danielle Cholewiak, a researcher for the Stellwagen Bank National Marine Sanctuary, conducted a number of song analyses on humpback whale songs. She adapted measurements in bird studies to analyze the songs of the whales. Whales repeat a phrase of notes several times in one block or "theme" before moving on to another. Cholewiak studied how often whales switched among these themes. She recorded whales off the Pacific coast of Mexico using recorders weighted with sandbags. After analyzing the recordings Cholewiak was able to determine the location of the singers and reconstruct their movements.
Fourteen cases were found where males sang alone for at least 45 minutes and then continued for another 45 minutes after another male started singing. Two changes were noted in the song when the humpback sang together; the first singers switched more often among various musical themes when there was a second singer and the first males adjusted their songs so the pair was more likely to sing the same theme simultaneously. When Cholewiak found a male singing by himself, she attempted a playback experiment. When confronted with simple recordings of their song, males tended to make their singing more even. A male came closer to spending equal times singing each theme. Researchers don't yet know what these changes in song mean but this new information allows us to get closer to the question of what messages whales may be communicating.
Posted By Tiffany Mallet
http://dsc.discovery.com/news/2009/10/23/humpback-whales-song.html?campaign=w01-101-ae-0002
It is so interesting how male humpbacks seem to be singing to eachother like male songbirds do. They even change their song like male songbirds do. I wonder if this is something that a common evolutionary ancestor had or if this evolved seperately. Perhaps this is a territorial thing. Great article!
ReplyDelete-Tricia Carlson
This is a great find! Did the article mention any additional behaviors that the whales exhibited? I would think if it were territorial they may show some aggression. You said that the article mentioned that after singing they swim off together, so maybe the singing is a way of finding relatives or family members. Also maybe the males are forming groups to go out and find females together like the crocodiles were doing in another one of the blog posts. Thanks for the interesting article.
ReplyDeleteJackie Connolly
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ReplyDeleteThanks for the comments! It would be interesting to find out some evolutionary history about the behaviors of the whales. Also, to look at other behaviors the whales displayed. Unfortunately, not many studies have been done on the whale and little is known. The article didn't say anything else besides the males just swam off together. I don't think it is a way of finding family or relatives because humpback whales were thought to be pretty solitary but who knows? There is a lot more to find out about this species and I think our increasing technology will let us do so in the future.
ReplyDeleteRevised by Tiffany Mallet