The days blend into each other in the High Arctic, where working nights under the 2 a.m. sun, or working days, is guided not by an internal clock or by the necessary stillness that comes with darkness, but by the cycles of the whales, which tend to be guided by the tides. At low tide, they seem to come closer to land, to rub and frolic in the shallows — which helps with their unique skin moulting — and it’s easier to watch them. Low tide is also when entrapments occur.
These temporary, and perhaps voluntary, channel entrapments or isolation events occur when whales swim across a shallow sandbar into a freshwater channel during the ebbing tide. As the tide continues to ebb the sand-bar becomes exposed, encircling the whales in their own natural pool until the next high tide.
It has taken place often enough this season (12 entrapments thus far!) to have provided a goldmine of information on contact call rates in relation to group numbers and group composition. I could not have hoped for a better natural experiment, with several important variables uniform across events (depth of the hydrophone, distance of the whales to the hydrophone, situation, and behaviour).
When I record the whales in their temporary river channel I know that I am not recording anyone else; the constant chatter of their 500 pals is either absent, or very faint (depending on the tidal stage), because sound does not carry well from the other side of the sandbar in less than one foot of water. This makes correlating group composition and acoustics much easier.
To add further value to these data, filmmakers Michael and Dave Parfit — who have joined me here to film this project as part of a documentary for The Nature of Things — and photographer Nansen Weber, have all contributed invaluable images and video of most of these entrapments. Estimating group composition accurately from the shore can be surprisingly difficult. When I compared my estimations with the videos, I found that I often underestimated the number of entrapped whales when groups were large (we had one entrapment of 38 whales!), because many animals look alike and rarely surface at the same time, and young ones can hide under the adults for long periods of time. The footage also allows me to count the number of calves, yearlings, juveniles and adults. I even rigged up an aerial monopod, duck-taping a very long aluminum pole to an equally long extendable pole that screws to a GoPro camera. That gives me a good 15 feet of elevation above the whales for even better accuracy.
I also regularly spend time recording the larger herd. The research tower works well for this, it’s a small (1×1-metre) platform built on steel poles, which one accesses at low tide. The key to a good stay in the tower is to follow these two simple Tower Commandments:
1. Time your exit with precision — there is a point beyond which it becomes impossible to leave the tower, even with waders, unless, of course, one is willing to swim;
2. Assume you might get stuck there, and bring food, water, and more clothes than you think you will need: the ocean wind can be ferociously cold.
I somehow failed to follow Tower Commandments 1 and 2 earlier this week. I was so absorbed by the whales that I missed the window of time to wade out of the tower; I proceeded to get stranded on it for eight hours . . . without a speck of food (a bigger deal than it sounds to my shrew-like metabolism), and fewer warm layers than I’d have liked. It was one of those “this is a little on the uncomfortable side, but too amazing to complain” moments. The whales slowly surrounded the platform with the rising tide. Closer and closer to me they came, many swimming on their side, bending their strangely flexible necks, one eye near the surface, clearly looking at me, then spooking at their own daring and swimming away with a tail flick, but back within a minute to take another look . . . the juveniles in particular were the most curious.
The whales and I eyed one another, intelligence-to-intelligence, curious beings wondering about each other. It is easy for us humans to feel a sense of empathy with belugas; despite our obvious differences (try using sonar to navigate ice leads in the dark) the parallels are large: we are both highly social, long-lived, intelligent and curious species, with long periods of parental care and offspring dependency, fundamental cooperation in raising these young, and loquacious to no end.
I observed mothers nursing their neonates right under the tower, babysitting adults with many young in tow, bands of juveniles cavorting around in that very tactile beluga-way, and what we presume is an all-male gang (they are larger, always together, no calves — we call them “the big boys”) roaming around the large herd as if one unit. And the recordings were fantastic. Since mothers and calves stream by the tower on their way up and down the river, amid hundreds of whales, this long tower session provided good information on the distinctiveness of mother-calf contact calls in beluga-chatter, in other words, how you can hear them clearly in a crowd. I waded out at 8 p.m. a little cold and hungry, but profoundly content.
It is now 3 a.m. and I’ve just returned from another great session. At midnight I scanned the delta from the research cliff; sure enough, it looked like there was yet another entrapment in the usual river channel. I was tired, I must admit. It was a long day, with an entrapment this morning and the afternoon organizing hundreds of gigabytes of data (sound and video). But my curiosity never fails to drive me: Are these entrapments intentional? Do the whales actively seek out some isolation from the large herd? If not, why do they happen so regularly, and why do we keep seeing members of the larger herd join the ones in the channel by laboriously “caterpillaring” their way into it inch by inch when the tide allows, rather than the “entrapped” animals rushing to get out? Are there any neonates in the group tonight (ideal scenario to test the idea that they make lower frequency calls, potentially more easily masked by anthropogenic noise)?
I packed my gear, hopped on the ATV and drove down to the delta. I was surprised to see only two adults in the channel, and they were calling loudly and continuously. I wondered if perhaps they could hear their offspring or their companions and they were responding to them. A large mass of whales crowded the other side of the shallow sandbar, including calves and juveniles. I could not hear their calls through my speakers (connected to the hydrophone), but perhaps the whales could. It is possible, I thought, that only the high frequency components of the contact calls (which are very broadband, 500 to 120,000 Hz) were getting through. Considering the less than half a foot of water covering the sandbar, this would make sense, since the shorter wavelengths of the high frequency sounds might get through the tight shallow space (much like Echosounders used in shallow water typically use higher frequencies — 30,000 Hz or more — than those used in the deep ocean). I need to look at the spectrograms, which will show me what my human ears cannot hear! But not tonight, as I am already in my double sleeping bag listening to the rhythmic blows and calls of the whales breaking the silence of this Arctic night.
For the second summer in a row, Vancouver Aquarium associate researcher Dr. Valeria Vergara is working in the Arctic. Based at Arctic Watch on Somerset Island, Dr. Vergara is carrying out acoustic research on the Cunningham Inlet belugas to learn more about wild Arctic populations, and to find out how their melting environment is affecting them. Her work is supported by the Vancouver Aquarium, the Weston Foundation, a Sea World Busch Gardens Grant, and Quark Expeditions.