Thanks very much Richard for your diligent work in identifying this bird. I have ordered a copy of the Warbler Guide and it should arrive in the coming days :-)
I reckon it's a drab Pine Warbler. The under-tail pattern and facial features should be diagnostic. Ref. Pg. 405 The Warbler Guide: dark cheeks, pale neck patch, large bill, pale supraloral, variable streaking below and variable yellow wash, wide white wing bars, long tail with large white spots = Pine Warbler. Sorted!
Many thanks for the input Richard. That does make sense as I do get Yellow-rumped Warblers occasionnaly in the yard during migration. The complete lack of any yellow in the bird makes me wonder as does the lack of any barring in the breast and sides...
