I have had time to go through all of my photos and found a few more that may 
all be the darker throated bird Hans Holbrook pointed out. This page also has 
museum photos comparing Caribbean and southwestern Cave Swallows with two 
southwestern races of Cliff Swallow. It is always hard to get the colors just 
right in museum photos, but I think these are close. There are very few specimens 
of fall or immature birds in the museum, so the comparisons are not as useful 
as they might have been. I also have a link to the Cayuga Lake, NY Caves 
photographed on Nov 25.


http://odolep.com/midatlantic%20birds/Cave_Swallow_Mont/csm.htm

Dave Czaplak