Michael and Tweets....Looking at Pg 452, plate 535 of Wheeler's
Raptors of Western North America, your photo is a near match with the
exception of the "partial white supercilium" of the photo in the book
of a female Boreal (dark type) Merlin. I don't see it in the O.S.
bird, but everything else matches.

Dianna Moore
Ocean Shores, Wa.
dlmoor2 at coastaccess.com