As I preceded closer to be able to see over a small ridge of sand, I noticed that one of the Caspian Terns looked odd. It appeared to have a deformed lower mandible at first. The bird walked closer to me and I was able to determine that it was a growth from beneath the lower mandible. It appeared to be a second bill. The growth was shorter than the lower mandible, so it did not appear to hinder feeding.
Very odd! Any comments to the contributing biological causes/factors welcomed.
**Update to the deformed birds. Was talking to another birder, Allan Claybon, who was there earlier in the day yesterday. He photographed this Bonaparte's Gull with 3 legs and another Caspian with the same bill deformity. Weird stuff!
Here is the link to his Flickr photos: http://www.flickr.com/photos/nsxbirder/6221946174/