Snowy Owl Visitor

My colleague Lori received an excited phone call from her husband Peter on Friday, saying that there was a Snowy Owl in a tree outside the suburban business park building where he works. The Snowy Owl was being pestered by many crows but it was resolutely standing its ground in a pine tree in the parking lot. We excitedly asked Peter to get some photos and send them to us. One of Peter’s colleagues dashed out and snapped these great photos.

So, what’s this owl doing in a parking lot in Ottawa? Snowy Owls breed on the northern tundra, and in some years many of them remain on their breeding grounds year round, hunting diurnally for rodents. Each winter, some Snowy Owls do migrate to areas of southern Canada and the northeastern US. Some winters, however, there are larger Snowy Owl “irruptions” where the owls are seen in larger numbers and in places where they are not regularly seen. It seems that this year is one of those times: Snowy Owls have turned up on Prince Edward Island in large numbers, and birding reports are replete with mentions of Snowy Owls in Ontario and the northeastern US.

What’s behind these southern irruptions? Conventional wisdom holds that Snowy Owls move south in the winter in years when their main prey source, lemmings, undergo a cyclical population crash. When food levels are low, the owls come further south searching for winter food. Something else that might be coming into play this year is that there was a very good breeding season for Snowy Owls this past summer, because lemming numbers then were high. This combination of a high number of juveniles in the population and what looks like a lemming crash this fall is what is likely behind this Snowy Owl irruption. Here’s a great listserv posting that further explains these two factors.
Looks like Eastern Canada might be in for a snowy (owl) Christmas!