This adult is 2 1/2 years or older as
indicated by three generations of secondaries: the
oldest secondaries are faded with frayed edges, two are faded but not overly
worn, and the newest are the darkest ones. Great Grays older
than a year have some plain dark primaries as on this individual.
Also note that some wing coverts
and undertail coverts are skeletonized, i.e. worn to the feather
shaft. The retention of considerable old feathering indicates an
inhibited or partially skipped molt that probably resulted from food
stress during the molt period before this owl irrupted southward. For more information on
molts and aging Great Gray
Owls see Pittaway and Iron 2005. Click on link below.