I saw what I believe was a Brewer's Sparrow Monday morning, April 30th at Springbrook Prairie Forest Preserve in Naperville, DuPage County. The bird was seen in the east side of the preserve along the grass/mowed trail (Henslow's Trail) east of Plainfield-Naperville Road. The bird was along the mowed trail where it parallels 87th Street at the south end of the preserve in an area of extensive mowed fields.
I initially saw the bird on the trail and immediately recognized it was something unusual due to its coloration and field marks. The sparrow had an obvious white eye ring with an otherwise very dull and unremarkable facial pattern, was brown-gray underneath with some faint and sparse breast streaks toward the sides of the breast. It also had very faint lateral throat stripes and no distinct crown stripe. The bill appeared light in color, as did the legs. The tail was dark in color and showed no white when it flew. At one point it was foraging near a Savannah Sparrow, and was about the same size or slightly smaller.
I returned to the location about an hour later with my camera, but was not able to relocate the bird. If I relocate the bird, I will post updated information.