Last year, I studied Boreal Owl sounds RELENTLESSLY in preparation for a
trip to Mount Ranier. I even learned how to produce the primary song by
mouth so I wouldn't need equipment if I felt I needed to whistle/solicit.
Without referencing books or guides before composing this note, I always
found Boreal song to differ significantly from Saw-whet in that it DOES
rise and fall. It seemed to speed up and rise in pitch and then slow back
down and fall in pitch - ever so slightly. Saw-whet is often as steady and
monotonous as can be, and it can sometimes be so darn fast it makes your
head spin. The speed of the Saw-whet song, in my opinion, can vary greatly.
I'm certainly no Boreal Owl expert, and I have no intention of challenging
your I.D. or suggesting it wasn't a Boreal, but I figured I'd share the
little bit of insight I may or may not have on the matter.
Good luck up there! I bet you'll confirm it sooner or later!
Rhett Wilkins
https://m.flickr.com/#/photos/boundtobird/
