This walk is really great, walk cycles can be really difficult to make look correct. The movements of the head when it looks around definitely give it a sense of life and personality.
There are a few things I noticed that were a little off. I am by no means an animation expert, so you can totally ignore me if you want! First, the left foot sinks into the ground during the beginning of the walk (which might not matter I don't know). Secondly, as the left leg steps down it has a quick movement as it makes contact with the ground. Just like it's stepping down to fast. I not sure if I'm describing it well. At my school we call it a pop. Anyway, it's pretty subtle. The last thing is the head movement when it turns forward again. It seems like it leads with the back of its head then turns to face front, instead of doing a full swing with its head. Again, I'm probably not explaining well and maybe that's how birds move.
This is just my opinion on it and it's still a fantastic animation, I'm just being nitpicky. Also, sorry for the long comment.