Frank, your doing almost as well with your new lens as you did with the 300/2.8, which borders on perfection. These pictures are great.
Your right, he was keeping his eye on you, looking like he was ready to flush.
I don't see any significant artifacts of over-sharpening.
I have reports of a osprey nest and roosting tree, probably closer to your house than the dam; almost the same drive up situation. I'll check it out this weekend. If I find it and it looks good, I'll let you know.
If you find anything to shoot, especially Osprey, please let me know. I went down to the UAH pond this afternoon and saw absolutely nothing. I'm ready to shoot.