This week we give the floor to our collaborator Valeria Vergara, a research scientist at the Vancouver Aquarium, who has been with us aboard the Bleuvet the last few weeks.
Bird’s eye viewing and underwater eavesdropping… by Valeria Vergara
The fog is so thick this morning on the St Lawrence River Estuary that you can practically lean on it. Finding a whale in this fog would be a daunting task, so we are staying put until it lifts. I am sitting at my temporary desk at CIMM (Marine Mammal Interpretation Center), home to GREMM (Group for Research and Education on Marine Mammals) researchers and collaborators, reflecting on the challenges and highlights of the past week. As a research scientist with the Vancouver Aquarium, I am here to study, with my old-time collaborator Robert Michaud (Director of GREMM), whether underwater noise introduced by human activities, an ever-increasing problem in the St Lawrence Estuary, is compromising the acoustic communication between beluga mothers and their newborn calves, and their ability to regain contact after separations. In a turbid underwater world, finding one another through vision would be as futile for them as it would be for us going out to look for whales in this fog. They must rely on sound to do this, more specifically, on a system of mother-calf contact calls.
But do mothers and calves really do become separated? How often does this happen? Do they call when they are apart? Are those calls masked by noise?
Eavesdropping on their underwater world with a hydrophone while simultaneously observing them from the air with a small, quiet drone to get a good view of their behaviour – including any separations and reunions – might provide us with some answers.
With each passing field day, fragments of the puzzle are slowly illuminated. Like the day we got confirmation that calves can indeed be occasionally separated from the adults. “The calf is alone, the adults left the calf absolutely alone!” yelled Mathilde, our drone operator, with her usual boundless enthusiasm, from under her cape (a contraption fabricated with a shower curtain that allows her to look, without the glare, at the ipad screen that shows her what the drone sees). When we reviewed the footage that evening this was crystal clear: a tiny calf was left alone for nearly 5 full minutes. He waited at the surface patiently until the adults re-joined it and the group continued on its way down the river.
Ten intensive field days have already gone by and I have learned this lesson (or rather, re-learned it, as it is a reality of many field research projects): good data days will be few and far between, and good questions take patience and more than one field season to answer. But I was also reminded – as I am every field season – of the absolute thrill of those occasional days when every factor aligns to produce an excellent piece of data. This was the case last Sunday: we had good weather with calm winds allowing for droning (we intentionally chose to work with a small, light, silent drone, but the drawback is that it cannot handle strong winds), cooperating whales that stayed with us the entire day, 2 newborn calves in the herd, and flawlessly working technology (not to be taken for granted!). In addition, we managed to stay with the same herd all the way down the Saguenay River, from the relatively quiet Baie St Margarite, where their calls could be heard loud and clear, to the deafening confluence of the Saguenay and the St Lawrence River, where all we could hear was noise. “Number of boats: 10! Ferry: 200-300 meters from hydrophone!” I dictated to Marie-Ana, my wonderful research assistant, who was taking time-stamped notes on the ipad. As I noted ever-increasing noise levels on the computer screen (I had to take my headphones off, so loud was the noise), Mathilde was filming the focal group with the 2 newborn calves slowly but surely crossing the ferry lane. “They are slowing down, as if waiting to cross!” she narrated. I can only imagine what it must be like for these acoustic creatures, tiny, naïve, new to the world, to traverse this literal wall of noise. It must be like having to crawl through a dark tunnel as a toddler. No wonder the adults slowed down!
A few more days have gone by since I began writing this blog, and we had a couple of successful paired sessions (flying over the whales and eavesdropping on them). I have yet to review my recordings systematically, but some contact calls were evident. Going over the material with the entire, excited GREMM team really brought home what the marriage of these two technologies can allow us to learn. The resulting level of detail is extraordinary. Calves swimming with one adult and then with another (indicating cooperation to take care of the young) perfectly clear nursing bouts, males engaging in beautiful play… And all this while listening in! After decades of classifying beluga behaviours into general categories that reveal too little, based on the small proportion of surface behaviours one can observe at eye level and at a distance (for example moving directionally, resting or milling), the barrier is lifted and we are suddenly allowed into their world.
Beluga sound excerpt © Vancouver Aquarium
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IDENTIFICATIONS OF THE WEEK