My favorite paper for painting birds so far is Sennelier Grain Torchon. I'm already finishing my 20 sheets block and going to restock on it.
Very pleased with the surface and colors staying intense when dry. It also holds water very well. I personally wouldn't use this paper for big wet on wet paintings, but for small, illustration kind of work it's a keeper!
Btw, I've added three new bird prints in my Etsy shop.