[obol] Yaquina Head Great Horned Owl mystery

From: Wayne Hoffman <whoffman@xxxxxxxx>
To: obol <obol@xxxxxxxxxxxxx>
Date: Sun, 8 Dec 2013 17:27:33 -0800
Hi -

On Nov. 2 I saw and photographed a Great Horned Owl at Yaquina Head hat
vwas very pale, and appeared to be of the NW Boreal Forest form.

Today (Dec. 8) a Great Horned Owl was roosting in a recess in the east wall
of the main quarry, opposite the visitors' center.  As I previously posted,
this owl greatly upset the resident Peregrines, who harassed it
extensively, but failed to drive it off.  This was also a fairly pale bird,
unlike the local residents.

I compared my photos from today to the ones from Nov. 2 and they are
clearly different birds.  Today's owl was also fairly pale, but had more
rufous than the Nov. bird, the black underparts barring was more closely
spaced, and it had some irregular blackish blotches on the upper chest.
 The "horns"  were also different, largely tan/rufous at the base and
whitish on the tips on today's bird, mostly blackish on the Nov. owl.  I
could not see much of the upperparts, but it did not appear as pale as the
Nov. bird.

In reading the relevant Oregon literature (Gabrielson and Jewett 1940,
BOGR) Great Horned Owls are described as resident, and no mention is made
of migration.  However neither of these birds looked anything like the
resident west side subspecies *Bubo virginianus saturatus, *so I have to
conclude they are migrants/dispersers from somewhere north or east of here.
Neither bird looks particularly like the ones in Oregon east of the
Cascades either.  Those birds have much more rufous, and strongly colored
buffy facial disks, very different from these birds.  The Nov. bird, as I
noted, looks a lot like the birds from northwestern Canada/interior Alaska.
Today's bird was also fairly pale, but not enough so for me to assign it to
that form.

The 1957 AOU Checklist included 9 subspecies of Great horned Owls from
north of Mexico (7 from the west), but more recently taxonomists have
lumped several of these.  Evidently, several of them are not as distinct as
first thought, but intergrade over broad areas.  It appears that the pale
boreal birds intergrade with the ones to the south all the way into the
Rocky Mountain states.  However, apparently the whitest birds are from far
north.  I am guessing today's bird might be from somewhere a bit further
south in that range.

So the mystery:  How/why would 2 nonresident owls show up at Yaquina Head
this fall?  Is there an incursion of these northern birds this winter?  If
so, is anyone else seeing "odd" Great Horned Owls?

Wayne
[obol] Yaquina Head Great Horned Owl mystery

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