Snowy Owls show up in Maine each winter and can be expected starting in mid-November. The highest frequency of Snowy Owls reported to eBird occurs in early December, and those that arrive usually remain through March. Observations collected by eBird illustrate this here: http://tinyurl.com/ksnou7x.
Some years only a few arrive, but every few years many more invade. In those invasion years, the earliest arrivals occur, and in the most massive invasions they have occurred starting in October. Longtime Bowdoin professor Alfred Gross (1883-1970) produced one of the finest summaries of these invasions covering the period 1833-1946. Click Here To view “Cyclic Invasions of the Snowy Owl and the Migration of 1945-1946.”
With at least eleven birds reported in seven days so far this November, it seems like we could be in for another good winter to see these magnificent birds.
Below is a summary recent reports:
As noted by Alfred Gross, in the truly big invasions, Snowy Owls show up earlier than this. During the 1945-46 invasion, Maine was the early alert center, with one at Kezar Falls on September 15th! The classic explanation is that lemmings, which are the main prey item for these owls, have cyclical population crashes (every four years or so). During these crashes we see a significant increase in the number of Snowy Owls entering the northern United States in search of food. Another possibility is that in years of extremely high lemming productivity, Snowy Owls produce many young that then must move to find food. Indeed, most invasions involve young birds at the southern limits, and these are often stressed individuals. So please respect them and observe at a distance.
Most Snowy Owls reported in Maine tend to be near the coastal regions. Abundance of birders likely plays a large role in the detectability of owls as well with most reports from southern Maine. Here are a few maps, past and present, to help you see where Snowy Owls are most likely to occur: winters of 2011-12, 2012-13, and currently.
Added to the Snowy mix, a Northern Hawk Owl has been present in Lincoln since 12 Nov and still be reported as of the 21st. Take a look Carl Alessi’s beautiful photo of the bird here: https://ebird.org/ebird/view/checklist?subID=S15683435
Contributed by Doug Hitchcox, Maine Audubon and Louis Bevier, Colby College.