A walk through Cook's Butte today in search of possible nesting Cooper's Hawk lead me to an extraordinary encounter with a male Pacific Wren singing on territory and nest building. They make the coolest nests! Thankfully, the coop eventually showed up briefly as a flyby while I was driving home - one picture. On a loosely related forest-bird-tangent - I tacked a few images on to the end of this post of possible small-owl nesting cavities that I've come across recently and then staked out for several days during the crepuscular period with no joy. Your thoughts on the images of the possible nesting cavities will be much appreciated.

Are you looking in the right place?  I wasn't and I was 20 feet away :-)

My original quarry

SMALL CAVITIES - dimensions of both openings are roughly 1.75 x 3" - estimated height of opening above ground is 3 & 9 feet, respectively.