I observed what I assume to be a pair of Peregrine falcons in the vicinity of the #51 building in Rockville yesterday (8 Feb) @  This is same the location where I observed a pair on 1 Feb engaging in inverted flying with talon presentation.  Subsequently, on 3 Feb one bird was confirmed to be a Peregrine by Andy Martin.  Yesterday, I was again first alerted to their return by vocalizations (several "chip" calls) and found them circling above the #51 building again engaging in inverted close-flying with talon presentation before they flew out of sight.  One bird may have been perched on the southern portion of the #51 building (this may actually be an adjacent building rather than the same building) at the time I was leaving the area @  I may have also observed one of the birds perched on the apex of the nearby "Clock" building on Monday 6 Feb @  Be aware that my observations are eye-only, but the appearance and behavior together with Andy's spotting scope assisted ID lead me to conclude that I am observing Peregrines.  I am observing from the Rockville MARC rail station platform, which is directly adjacent to the Rockville METRO station.

Jim Speicher
Jspeicher-at-niaid.nih.gov
Rockville @work :(
Broad Run_S. FRED Co @home :)