This is the best position when communicating with a crow:  proximity,  full attention; eye contact.

I had never sung to a crow when thusly engaged.

The results were startling and wonderful. 

First it puffed up the head feathers, then the cowl feathers and finally the back and breast.  Slowly it lowered them all.  And then it opened its beak!

I finished the song and sat there in silent amazement.