The great blue heron rookery is easily visible now in North Mississippi Regional Park. I had to give a program there on Saturday afternoon and the nest building birds were a treat to watch. The trees haven't leafed out yet and so you can make out which nests are still under construction and which already contained incubating females.
I was very interested to note a great egret perched among the great blue herons (wasn't able to digiscope a photo)--will this colony diversify to other species? Speaking of which, not everyone is happy to have a heron rookery in their neighborhood. There's a news story from Kentucky of some residents who have gone so far as to cut down trees to keep nesting black-crowned night-herons from nesting over their homes.