[Tweeters] Pair of Tundra Peregrine Falcons (?) over the MontlakeFill today

Martin Muller martinmuller at msn.com
Sun Feb 1 22:25:13 PST 2009


Apologies if this is the umpteenth response to your posting.
I'm on digest mode and it is now Sunday evening....I haven't had time for email for 48 hours.

I'd just go for Peregrine Falcon.

The fact that you describe both birds as the same size pretty much rules out a "pair." Tiercels (males) being a good deal smaller than the falcons (females).
The behavior you describe nicely fits a territorial dispute between adults peregrines. Why would two migrating tundrius peregrines perform that kind of behavior over Seattle?
There's a nesting pair just southwest of the UW district (Ship Canal Bridge).
Today (Sunday) Ed Deal and I lead a Seattle Audubon Society field trip looking at Seattle's peregrines (saw ten individual birds).
Many of the adults look pretty pale on the back. Their feathers are getting 'old' and bleached. Especially some of the males we saw today looked very 'silvery' on their backs.

>From my own experience I know that from any substantial distance (especially with binoculars) the whole front of a peregrine can look absolutely sparkling bright white, under the right lighting conditions. Then when you get a close-up look with a scope the same bird's front dissolves into the finely speckled -including tear-drop shaped spots-, or even cinnamon-colored front of some of our locals. The contrasting darker belly you describe fits well with the barred front of adult peregrines.

While not ruling out your suggested id to subspecies, without a close-up look I'd assume at least one of the birds is one of our locals.

Martin Muller, Seattle
martinmuller at msn.com<mailto:martinmuller at msn.com>

----- Original Message -----
From: Kevin Purcell<mailto:kevinpurcell at pobox.com>
To: Tweeters<mailto:tweeters at u.washington.edu>
Cc: Kevin Purcell<mailto:kevinpurcell at pobox.com>
Sent: Friday, January 30, 2009 6:03 PM
Subject: [Tweeters] Pair of Tundra Peregrine Falcons (?) over the MontlakeFill today

Out walking the Fill in mid-afternoon around 3pm after wondering were
all the passarines were (the breeze was up but the sun was still
peaking through the high clouds).

I noticed a pair of bird flying tail astern. Falcon shaped. Medium
sized (bigger than a crow?).

In the bins they were clearly interacting each trying to get the high
side of the other and dropping talons inducing the lower bird to
roll. After a couple of interactions like this they split one heading
back up to the UW and area to the west of it by circling and climbing
under power (with the occasional soar but there wasn't much
convection today). The other I lost track of. He stayed in view (in
the bins but at rather great distance) for between 5 and 10 minutes.

Unfortunately that initial encounter of the pair was a close as they
came to me when I was thinking more about behavior than field marks.
But even when circling I got a good view of the underside and the
upper side.

I was a little puzzled. They were both the same size and colored the
same: light gray or light bluish gray above and whitish underneath.
Both clearly with falcon wings and flight style (no flap, flap, flap,
glide). So it's a falcon.

As the bird climbed I could see the "head" (i.e. the underside and
side of the throat and face) looked clearly white and the underside
of the body a bit darker but not quite grey. The upper side of the
body and wings was uniform light bluish gray (certainly not dark gray
or dark blue). The tail didn't have any clearly obvious barred patterns.

I'm not great at falcon id (not seen enough of them to know the
details first hand) but this had me a bit puzzled. I didn't see any
red or brown on the upper surface or strong tail barring plus the
size seemed wrong (not delicate) ruling out a American Kestrel. Again
no dark blue upper surface and no tail barring ruling out a Merlin.
No dark axiliaries so not Prairie Falcon (and it's out of
range ... :-) ).

So that leaves a Peregrine or Gyrfalcon. So two Gyrfalcon over
Seattle would be a bit too incredible. Plus in the photos and
drawings I've seen of Gyrfalcon they seem more bulky than this.

So I get to a Peregrine. but shouldn't it be darker above?

In "Hawks in Flight" I see they mention the subspecies tundrius as
"Adults are light grey above. Some individuals show a blue-gray cast
on the back and tail. The paler tones, coupled with a more restricted
facial pattern, mute the bold helemeted appearance of the anatum".

This is a very close match to what I saw (including the white "head").

So I believe I saw a pair of Falco perigrinus tundrius over the Fill.

Comments welcome.
Kevin Purcell
kevinpurcell at pobox.com<mailto:kevinpurcell at pobox.com>

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