While walking along Mass Ave this evening, I saw a very impressive whirlwind of Chimney Swifts over the Greenbriar building at 4301 Mass Ave, NW.  I didn't stop to do a good count but I wouldn't be surprised if it was around 2000.  I haven't seen reports of this as a major staging spot before, so I thought I'd mention it for those interested in swift movements. 

Jason Waanders
NW DC
jwaanderATstarpower.net