I grew up fishing in areas where you would see a few of these every day.
Last year when I went back and fished the Indian River Lagoon, I saw DOZENS. It seems that most of the inland islands have been developed.
There are only a few that have been set aside as natural reserve (thanks to many battles betwixt the locals and the yankees)......all the birds concentrate there now.
So you can see MANY if you fish close to the reserved islands, but it seems there are less in the lagoon by large.