For a few reasons, I'm not crazy about birds' feet. Not that they smell or anything, but they're scaly, skinny, generally not too attractive, and they're hard to figure out how to draw and paint. I've known for a while that the back toe on the feet of most perching birds is the equivalent of our big toe, and it's not jointed, so it doesn't wrap around a perch like the others do. What I found out today is that the other toes have different amounts of joints, and I've been studying diagrams to help me do the best job of making them look accurate. Who wants to lose a sale because a knowledgeable and particular customer says, "I'm not going to buy that painting because you should know that the third digit has three bones, and I only see two." That's not highly likely to happen, I know. However, I can tell when looking at another artist's work if they have really observed and are educated about their subject. Once, a bird artist I met at a show, a wood carver, pointed out to me that he could tell I knew my subject because my bird's back toe was straight, not bent. Believe it or not, I was flattered by that comment.
I found this very simple yet very helpful drawing from a Google search for bird foot anatomy. It was done by an artist named Jack Laws. I hope I have given him enough credit for this drawing!