This individual represents the first record for Northern California. It shows characters suggesting a member of the curvirostre Group which includes T. c. celsum, T. c. oberholseri, and T. c. curvirostre. Prior California records have been attributed to the palmeri Group characterized by lack of wing-bars, smaller tail spots, darker underparts, and less contrasting ventral spotting. In addition this bird shows the breast spots clustering in the middle instead of being spread uniformly. Note also the sharp contrast between the white throat and the breast on this bird. In the palmeri group this transition is more blended. The tail spots are bright white on our bird. In the palmeri group they are grayish-white and much less distinct. In 2009, the AOU considered a proposal to elevate the palmeri Group to full species status. However this proposal was defeated pending further research.
This individual seems to be a reasonable provisional match for T. c. celsum which has spread as far north as southern Colorado and Kansas. It is described as more buff on its underparts with whiter tail tips cf. nominate. However, these races intergrade and some authors consider celsum and oberholseri to be a synonym of curvirostre.
