Pileated Woodpecker

I have seen a Pileated Woodpecker once before in my lifetime. The Pileated, for me, is one of those glamor birds; big, beautiful and elusive. So, when I had my first sighting, it was a trill. Still, it wasn't fully satisfying as I saw the bird at the Portland Audubon Society's suet feeder from inside the visitor center. A legitimate sighting, but kinda like fishing at a fish farm.
Sighting number two.
As I mentioned on Thursday, I had intended on spending the morning at Fernbank Forest in Atlanta, but was turned away when I got there since access was closed to the public until after 2:00 PM. So I hiked about four or five blocks away and spent some time at Olmsted Park.
Olmsted was quite an active park. After about an hour or so, I heard a loud bird flying into the park. I looked up and saw a large black bird through the branches as it flew above the tree tops. It swooped down and landed on the side of a the trunk of a large tree not far from me. It was obvious that it was a Pileated Woodpecker.
The lighting was difficult as the sun was behind the bird and the bright sky streaming through the leaves served as the background. As I took pictures the best I could, I noticed a couple of interesting behaviors. First, it bobbed back and forth, swinging its large head from side to side. I'm not sure what this behavior accomplished. Second, it stuck its head down upward facing knot holes in two different trees. I assume it was either looking for food or drinking water. Heavy thunder storms had passed through the day before dropping a lot of rain, so the holes could have had water in them.
Another thing I noticed after looking at the photos on my computer was the large hole in the side of the tree not much higher than where the Pileated had landed. I wonder if it was the bird's nest?
All-in-all, quite an exciting sighting.