Progress on nuthatch bird painting

The pair of red-breasted nuthatches (diptych painting) is progressing well today.  
I have begun to differentiate the two birds at this stage, and you can now see that the male has a deeper rust on his chest when compared to the female on the left.  Another distinct difference is that the male sports a black crown while the female's is dark grey (although the angle of the male's head makes it a little difficult to discern).