As others have said already, being a high-arctic breeder Snowy Owls really have no choice but to hunt in daylight because there is little or no night during the summer. This, I would guess, is what the textbooks are referring to. The opposite will be true during the winter for the many birds that stay north, when the night is long. Also the owls will have the prey to themselves when strictly diurnal competitors such as Rough-legged Hawk and Golden Eagle are roosting. So to persist in the far north the species must be quite flexible relative to other owls and this would come in handy when birds irrupt southward.
Speaking from a coastal perspective, I've never seen a wintering Snowy actively hunting during the day time. They certainly move around, occasionally spar with others when present, dodge attacks from Short-eared Owls or hawks and are generally vigilant but don't seem to be hunting per se. I've routinely seen them become much more active at dusk, presumably in preparation for a night of hunting. It would be interesting to hear if this rest up during the day and hunt by night holds true for birds wintering on farmland where they target different prey from those on the coast. Many will remember the Snowy Owl that frequented Piermont Pier (Rockland Co.) in Februrary 2007. This bird dined on Ruddy Ducks snatched from the sheltered bay, bringing them back to a perch where the pile of discarded heads and feet attracted a most splendid adult Ivory Gull. My recollection was that the owl fed mostly at night but maybe someone can confirm or refute this. A priori, it would seem a lot easier for the owl to swoop down on roosting ducks (and as we've heard roosting gulls) under the cover of darkness when it has the visual advantage. Phil Jeffrey has posted pictures (albeit gory ones) of the polishing off a stiff tail. http://philjeffrey.net/piermont2.html Bottom line, individual Snowy Owls can probably adapt their feeding/roosting cycles to fit the available prey. I imagine they also hunt less and roost more if food is easy to acquire during optimal periods. With so many owls around this year, it would interesting to learn from field observers what the current birds (largely immatures by the fact that most are very heavily barred) are feeding on and when they do so. One more reason to view from a distance and let them to do their thing. Angus Wilson New York City -- NYSbirds-L List Info: http://www.NortheastBirding.com/NYSbirdsWELCOME http://www.NortheastBirding.com/NYSbirdsRULES http://www.NortheastBirding.com/NYSbirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/NYSBirds-L 3) http://birdingonthe.net/mailinglists/NYSB.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
