Friday, October 19, 2007

Songs of the humpback

-- by Dave

Humpback whales were hunted out of northern Vancouver Island's Johnstone Strait back in 1967, when whalers still plied those waters, and it's been years since they've been back in any numbers. I've been kayaking in the Strait three times and have heard that one or two might be about each time we've gone, but never saw one.

Apparently, they've become surprisingly common there this past year, according to Paul and Helena Spong at OrcaLab on Hanson Island.
After being totally eliminated from Northern Vancouver Island waters in 1967, humpback whales are gradually making a return. The Coal Harbour whaling station, on Vancouver Island’s northwest coast (near Port Hardy) was the last whaling station in North America. In 1967, faced with a shortage of whales in nearby Pacific waters, the whalers travelled around the top of Vancouver Island into Queen Charlotte Strait, Blackfish Sound and Knight Inlet. There, they found a tiny remnant population of 13 humpbacks. Every last one of them was killed - all the males, all the females, all the mums, all the kids, everyone.

A long period of silence followed. Then, on Easter Sunday in 1982, a lone humpback was spotted traveling east past Alert Bay towards Johnstone Strait. Possibly, this explorer brought news to other humpbacks, because in the years that followed, humpbacks gradually began to return to these waters. Their pace was slow at first, but by the turn of this new millennium, humpbacks had become a common enough sight that they formed a reliable part of the whale watching scene. Nowadays, whale watch operators who can’t show orcas to their passengers can almost count on humpbacks to fill in the gap.

Interestingly, the humpbacks who first arrived were never vocal, so far as we could tell from listening to our hydrophones. But over time, they began to make a few tentative sounds. Last year, on October 14th, we made a wonderful recording in which the A30s and a humpback were vocal at the same time in Robson Bight. We had no idea whether this was some kind of interspecies exchange, and it didn’t last long, but it did make us reflect on the comfortable presence the humpbacks have become in these waters. This year, we have become even more convinced that this is so, that the humpbacks are truly at home here once more. Not only are they here in greater numbers than ever, but they are becoming more vocal. This year, on September 11th, we recorded a 10 minute long vocal session from a humpback in Blackfish Sound, and on October 11th we recorded what sounded like a complex “song” that lasted a full half hour. Here it is: click for audio clip (150mb).

The link is a .WAV download that's fairly large, but quite safe; it contains about a half-hour of humpback whale songs (with an odd orca call thrown in here and there) that is remarkably clear and crisp. (I've downloaded it onto my desktop and have it playing now for ambient music.)

There's also a piece in the Times-Colonist detailing their return and Spong's audio recording:
The unique series of whale phrases and repetitions occurred in Blackfish Sound at the southern end of Queen Charlotte Strait. Its length and complexity signals that the humpbacks may finally be feeling at home in West Coast waters again. "It's a safe place for them to come -- it's also a place where they can find food."

Humpbacks feed on herring and pilchard, among other small fish.

Spong doesn't know how many humpbacks might be cruising B.C.'s coast, but notes that Port McNeill biologist Jackie Hildlreing has a catalogue of 77 humpbacks observed in West Coast waters. They're common enough to be seen as integral to the whale-watching business.

The repetitive phrases of humpback sound compare to verses in songs, explains Spong, a psychologist. Orca calls are commonly heard by OrcaLab but are not repetitive in the same way as the humpback song.

"In general, the songs are thought to have a role in mating," says Spong, perhaps as a form of male display to impress females.

Most of this big humpback song appears to be in the voice of one whale, almost certainly a male, although toward the end there's an indication another humpback may have joined in.

"It was just amazing," said Spong. "It was such a thrill for us to hear the sound."

I've written about Spong and his work previously. He's a remarkable person, and it shows up in the work he produces.

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