At first glance, it looks like a Chipping Sparrow. When it's with other chippies, it stands out and looks different. The lack of dark lores might indicate a Clay-colored but pretty much everything else says Chippie. The rump appears gray in the upper left photo. The underside appears to be gray with some hint of buff. By itself, the cap occasionally looks to have some reddish brown but it stands out as brown and not red when with other birds. It has a fairly distinct median crown stripe. There is no strong bordering of the ear coverts although there is a small portion of a dark line that is occasionally visible on the lower border below the ear.