Again this summer, I was part of a crew heading up North to one of the primary snowy owl breeding grounds in the Eastern Canadian Arctic. There, from mid-May to late-August, a team of 25 to 40 people from all spheres of research (plant, mammal and bird biologists, field assistants as well as local Inuit) devoted themselves to studying every inch of the magnificent tundra landscape.
Each year we have the same question: Will it be a “snowy owl year”? Indeed, our long-term ecological monitoring on Bylot Island in Nunavut, Canada, has made it pretty clear — lemming populations fluctuate tremendously from year to year and so do the owls that feed heavily on them.
When lemmings reach peak abundance (which happens roughly every four years) — and only during those years — snowy owls invade the site and nest in big numbers. Because summer 2014 was a banner year for both lemmings and owls on Bylot, odds were low for summer 2015 being a good nesting season (Only once over the last 27 years of monitoring did snowy owls nest on our study area two years in a row.)
And the predictions held true. There were some lemmings this summer, but the numbers were not high. Thus it was no surprise that we found no breeding owls on the 500 km2 study area that we survey every year.
Nevertheless, it was a very nice and productive summer. The research and monitoring go on, even if no owls show up to breed. From a scientific point of view, counts of zero are worth as much as any banner year (although they are of course less fun).
There were also plenty of other projects going on this summer on Bylot Island. Monitoring of cliff-nesting raptors such as peregrine falcons, gyrfalcons and rough-legged hawks always brings a thrill. Moreover, we succeeded in deploying the first GPS/GSM transmitters on rough-legged hawks on their breeding grounds in North America.
As for the snowy owls, chances are that they nested somewhere else in the vast Arctic tundra where lemmings were more numerous this summer. Indeed, the owls that we have tracked since 2013 and 2014 as part of Université Laval’s satellite telemetry project settled and likely bred on Baffin and South Hampton Islands in northern Canada. We have no confirmation on the success rate of those nesting attempts, however, or on the lemming situation at those sites during summer. Moreover, Russian and Norwegian colleagues have reported fair numbers of breeding pairs on their side of the globe. (The Yamal Peninsula in Siberia apparently had particularly high numbers of breeding owls.)
In North America, the only two other sites that I am aware of reporting breeding owls in this summer were Barrow, Alaska (where long-time researcher Denver Holt found three nests) and Bathurst Island in Canada (for which I didn’t have any precision on the number of pairs, but their presence was confirmed). That doesn’t mean that there were no other sites with breeding snowy owls in North America. But since most snowy owls creating a major winter irruption are young birds dispersing south for the first time — and given the low density of nests so far reported from the North American Arctic — I would predict a slower winter, at least in the eastern North American states.
However, snowy owls have a tendency to surprise us and to do exactly what we didn’t expect, so we’ll have to wait and see what might come to our latitudes this winter. Indeed, some early reports of snowy owls (as of 15 Nov.) have already been heard from Wisconsin, Michigan, Minnesota and Saskatchewan, to name only a few places. However, this broad region is known to be used regularly by wintering snowy owls, so this might only be “regular” movements. The same may be true of the handful of reports from the Northeast as far south as Pennsylvania. In any case, we’ll keep you updated as the winter of 2015-2016 unfolds.
(SNOWstorm team member Dr. Jean-François Therrien is a senior research biologist at Hawk Mountain Sanctuary in Pennsylvania, and has been studying snowy owls in the Arctic for years with Laval University in Quebec.)