For that shot I waited until the resident red-shouldered hawk flew past. Also, as with any wildlife photography, patience pays off. I had been waiting for an opportunity to photograph a night her on for 2 years when I happened across this nest. I had seen other nests but the tolerance zone was a formidable 40 - 50 yards even in mangrove forests. Remember also that the more people you attract to the nest the more you will disturb it.
Groups of people tend to surround things to get a better view.
The surrounding of any animal will cause it anxiety. Last year I witnessed an incident in Denali where a group of people surrounded a Caribou. It panicked and ran through a crowd of senior citizens at a bus stop. In this case he was told by others at the scene not to go behind the caribou but elected to ignore their advice. He received a humiliating lecture by a ranger and a warning for his actions there.