[Ontbirds]Great Gray Owls: Aging & Variation

[Jean Iron]

With today's report of a Great Gray Owl from Wye Marsh in Simcoe 
County and last Monday's sighting in Algonquin Park, we may see more 
Great Grays in southern Ontario. The last irruption of Great Gray 
Owls, one of the largest ever recorded, was in the winter 2004-2005. 
It was fully documented in three major articles in the December 2005 
issue of Ontario Birds 23(3):105-160. In that flight there was only 
one confirmed first year bird (Mark Peck, pers. comm.). Most were 
adults with considerable old and faded feathering, which normally 
would have been molted, but was retained because of food stress (no 
voles). The lack of voles in 2004 also explained the absence of first 
year birds because most Great Grays did not breed or failed. This 
year's vole crash occurred much later (fall 2007 compared to spring 
2004) so there should be proportionally more first year birds this winter.

If you see a Great Gray Owl, try aging it using a scope. They are 
fairly easy to age as either first year or adult. See our online 
article "Aging and Variation of Great Gray Owls" 
<http://www.jeaniron.ca/GreatGrays/index.htm>. Using photos we 
discuss the plumages and molts, subspecies, morphs, albinism, 
melanism, and telling males from females.

Please give tame boreal forest owls the space to hunt. Do not pursue 
them paparazzi-style. They are hungry and often starving.

Ron Pittaway and Jean Iron
Minden and Toronto ON