Today (10/3) at about 12:25 Tom Gilg and I identified a Yellow-throated Warbler at Hewlett Packard in Corvallis. (Unfortunately access is restricted to people who work there and people escorted by HP employees.)
I first heard warbler chip notes in the vicinity of the fruit trees that are along the fence west of the cafeteria, then heard chip notes in flight, going north. I then spotted it flying from a conifer to the very tall conifer that is near the cafeteria and the closest one to the lake.
It flew into a dense clump of fir at the end of a branch about half way up the fir tree. Tom and I both had brief glimpses as it worked its way through the clump. Finally it fully emerged for a brief view before flying to another branch, then it disappeared. We watched in vain for another 15-20 minutes but saw no birds in that area.
I was first struck (during brief glimpses in the shadows) by the yellow throat extending to the lower breast that had me thinking Yellowthroat. When it emerged, I finally had a view of the black mask and white eyebrow. I also noted the white belly and undertail coverts and a lack of any other yellow on the bird.