Snuck (sneaked?) over to Blue Mash for about an hour and a half this 
afternoon.  Just before turning into parking area, a falcon flew across 
Zion road.  Stopped the car and got quick look at what I believe was a 
Merlin.  Medium darkish underneath leading towards an even darker tail.  
A few moments later it flew back at a much higher altitude and joined up 
in a thermal with a larger falcon and a Black Vulture.  The second 
falcon was about a 1/4 to 1/3 larger.  Don't have a lot of falcon id 
experience (except Kestrels) but the possible Merlin appeared a little 
on the large side (based on one I saw at Hughes Hollow last spring that 
was id'd by group consensus) and I could discern no buffy undertail 
coverts as illustrated in Sibley.

Other than the falcons, things were quite slow.  The larger pond held:
Great Egret, 1
GB Heron, 1
Green-winged Teal, 14
Mallards
Wood Duck, 2
Killdeer, 9

Also got out to Violette's Lock between 7 and 8 AM, 3 times this week 
hoping for something unusual but it was very slow.  The river is lower 
than I've seen it in many years.  Best birds were a couple of immature 
Bald Eagles (Thurs.) and some good looks at an Osprey. 

Good birding to all this weekend,

Andy Martin
Gaithersburg