Downy Woodpecker (Picoides pubescens)
He stayed in one tight little area the entire time I watched, and with the abundance of waving branches and leaves between us I had a hard time getting any decent shots of him. It wasn't until I got the pictures downloaded to my computer that I saw the hole that was keeping him so busy.
In one (rather blurry) shot, it looks like his entire head and upper body are plunged inside this cavity.
So as I'm still pretty new to all this, I don't feel too stupid asking the question. Is this a nest under construction, or is this guy just really getting ambitious in grub-hunting? Is there an easy way to tell?
For some great bird photos from around the world, check out Bird Photography Weekly #20.