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Juvenile Spizella sparrows can present problems in the field. We have many Chipping Sparrows (S. passerina) nesting at our site, although we net very few in our banding area. At first grab, we assumed this was a Chipping (hereafter CHSP), but noted the gray collar was quite prominent. While CHSP are small birds, this bird was distinctly tiny. A wing chord measurement of 57 mm put it out of the range of CHSP, and at the low end of the range for Clay-colored Sparrow (CCSP). |
The lack of a full eye ring, the unstreaked gray collar, a moustachial stripe that thickens behind the eye, and measurements eliminate Brewer's Sparrow (S. breweri), a species that has been recorded only once in Michigan. |
Facial pattern is an excellent way to distinguish juvenile CHSP from CCSP. In these photos, note 1) the eye line in CCSP (above and left) does not extend through the eye to the lores; in the CHSP (below) it does, giving them dark lores, and 2) the eye line in CCSP is as distinct as the moustachial stripe (the stripe that leads from the middle of the bill down past the eye); this is pale and indistinct in CHSP.
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CCSP generally have very few streaks on the breast, whereas CHSP would have more streaking while still in juvenile plumage. |
 
The rump of CCSP (top) is brownish and does not contrast greatly with the back, while in CHSP (below) it is gray. |
