I received a correction to my possible Slate-colored Fox Sparrow from Steve Hampton:
This is actually fine for Sooty Fox Sparrow, based on the brown (not gray) back. Northern Sooty forms show a lot of gray in the face and all forms show red tones in the wings and tail (especially in good light, which they tend to avoid). All Fox Sparrows have yellow in the bill in winter, which becomes pinkish in summer. Slate-colored have much more pale gray in the face, no brown in the crown, obvious gray backs, and more bright orange tones in the wing and tail. See the cover photo at the Fox Sparrows Facebook group for Slate-colored and Sooty side by side. https://www.facebook.com/groups/447117322159681/
I wish I had time to record his song; maybe next time. The dialect sure sounded different from the usual Seward Fox Sparrows.
Many thanks to Steve! Check out his photos and explanations on the above link. Always more to learn!
Seward Sporadic Bird Report Reporter