Hoping for some input on the range of the two species of chickadees in 
Maryland.

We haven't birded western MD very much and were wondering at what point 
the range of the Carolina Chickadee transitions to Black-capped Chickadees. 
We hiked about 12 miles of the C&O Canal towpath yesterday starting in 
Hancock (Washington County) and moving west. Along the way, we studied 
some groups of chickadees, trying to determine if we thought there were any 
Black-capped Chickadees. Of course, all of the chickadees' feathers were fairly 
worn. At times, we had ones with very gray secondaries and at other times, 
ones with more white on the secondaries.

We've always seen Black-capped Chickadees out of state where Carolinas 
were not present, making it a little easier. Is it possible we were seeing a bit 
of both species in this area of Maryland?

Thanks!

mln and dcs