Debby Kaspari - New England Sketchbook
Pine Warbler - Drawing the Motmot's North American Birds journal
a duck sitting in a lake sketch
LOTS and LOTS of painting and drawing tutorials and references on this site! North American Bird Sketches, Critters etc.
Debby Kaspari bird sketch "Draw a Bird
More Chris sketches. (orig text is great: Field journal example. This is a fabulous example of studying the anatomy of a bird, its posturing and personality.