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.
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.