From an Arlingtonians for a Clean Environment friend who's a major birder:
This seems to be a good winter for Cooper's Hawks. In your neighborhood, keep an eye out for (endangered) Peregrines. We lived for a year in Randolph towers on the 20th floor and would often see one when we were out on the balcony. I suspect they nest on some high-rise there in Ballston.Any cool hawk sightings to report?