That is a shame that they destroy the trees. I did a Google search to see what you were talking about.
Ill have to try and get down there at a different time of day, not sure if ill see those there again but there seems to be allot of larger birds in the area, usually i cant tell what they are because there to far away.
I got to try out A 500mm lens so I was able to get a few pics, they were still pretty far away except for one of them that was swimming around, the rest were all way back near the other side of the lake. I am not sure how you get to the other side but I can see that people over there are on hiking trails occasionally.