Evidence of Change

Seals  Favourite inhabitants—Sable Island Harbour Seals. Photo David Coltman

I made 7 trips to Sable Island during my Phd studies between 1992 and 1997. My doctorate was on harbour seals, so I normally went to Sable from May to early July, but I also came to Sable to participate in fieldwork on gray seals during couple of January seasons. One of the things that stayed with me from my time on Sable is an appreciation for how rapidly things can change with time. Of course, we are all concerned with rapid and unexpected environmental change, and those of us who are ecologists and evolutionary biologists study how living things cope with change at different temporal scales, especially in light of climate change. For me, Sable Island epitomizes change at many scales.

Perhaps most obviously and immediately, the weather on Sable Island can change unpredictably, rapidly and consequentially. I remember standing on the beach near East Light at the end of a long gray seal January season watching the sky for a survey aircraft to pass over and count seal pups. I had stayed late with part of the team to ground truth an aerial survey of the island, and the aircraft had been trying for days to find window of clear skies to complete the survey. It was late in the pupping season, so this was the last day we could attempt to complete the survey and we were packed and ready to leave for home immediately after completing it. Blue skies held long enough for the plane to reach Sable from Halifax. As we could see and hear it turn towards the island, the winds picked up, black clouds rolled in from the southwest and snow started to fall. No survey; and we were stranded for more than a week until the weather would clear and Gerry could find a runway. I also remember a pair of contractors who came for a weekend to complete renovations to BIO house. They arrived with the clothes on their backs and the smokes in their pockets. 2 weeks later the fog cleared and they could go home. On the other hand, the weather behaved perfectly for Pierre Trudeau the day he came for a picnic. One of the highlights of my time on Sable was the few minutes I blathered to Pierre about my research. It was an honour and a privilege to meet him there; I just hope I didn’t bore him.

Less immediate, but equally dramatic, are the changes that happen over a few years, or at ecological time scales. I watched fewer and fewer harbour seals return to Sable the years I was there, but the number of gray seals increased exponentially, as did their use of the island. The vegetation continued to spread towards the spits, and dunes shifted and grew, or they blew out and disappeared between seasons. Of course, when the sands move and shift they often reveal evidence of the past: wrecks, ruins, and sometimes the remains of past denizens. A fossilized walrus jaw sits on my shelf, beside a pulley from the ruin of a lighthouse or station. These treasures are evidence of change in the past, and change is perhaps the only certain thing in the future of Sable Island.

David Coltman, September 2009
(Professor, Department of Biological Sciences, University of Alberta).