This is done with watercolors. I struggled with the wings and lifted entire sections 2 times, which roughened up the paper a bit. But now I understand bird feet a bit better!
I like that you went ahead and tried acrylics. I stuck with my watercolors and also had trouble with water management with the water brushes. To get the finest lines, I had to squeeze the bristles with a towel to make sure I didn't have too much water. I do like how fine a line you can get with the stiffer water brushes. I like how your cardinal turned out.
I also had to pay extra attention to keep my base layer light so the bird was backlit. Your bird is just flying around on a cloudy day ;-). I like how it looks like the bird is looking right at me.