Chipping Sparrows and American Tree Sparrows do look very similar. Chipping Sparrows have a black line through their eyes and American Tree Sparrows have a reddish line through their eyes. American Tree Sparrows are also larger. You likely saw American Tree Sparrows if it was winter. Chipping Sparrows are very rare in the winter here.
My Chipping Sparrow is still here waiting on other Chipping Sparrows that will arrive soon. It has toughed-out a very nasty winter and was a first on eBird for my region and time of year.
