Music Mountain  Stockbridge, VT

Today--all day-- two birds were flitting around in the white birch in the
yard.  They were gray  with a yellow patch on their wings  ( similar to the
red patch on a Red-winged Blackbird) and some more yellow on top of the 
head.  One was puffed up--and kept fluffing up its feathers--size about like
a junco and round in a similar way.  Any ideas would be appreciated.  The
underside of the tail was black and white.