Some other suggestions for these two target birds: (1). Yellow-crowned Night-Heron has been breeding in Sligo Creek Park during the last couple of years, although I can't provide a specific location. Moreover, Claudia Wilds indicated that these birds can also be found along Sycamore Landing Road. (2). Upland Sandpipers have been reported along Oland Road in Frederick County, although I can't recall the specific dates.