I know this will sound ridiculous, but if you're looking to photograph nesting birds in March in Orlando, you really should consider visiting Gatorland (
http://www.gatorland.com/)
Behind the main display areas, they have a large swamp where they let their domestic alligators roam around. There is a wide boardwalk and an observation tower in this area. People feed the gators hotdogs.
Huge numbers of wild birds have moved into the area to nest. Many nests are within 6 feet of the boardwalk! The Gators eat any raccoons and possums that otherwise might attack the nests. The birds fish but also eat the hot dog bits that people drop or give to them. (Gatorland doesn't own the birds.)
We were there in mid-March and you could end up within "point and shoot" camera range of nests with eggs and some with chicks of
-Great Egrets
-Snowy Egrets
-Tri coloured herons
As far as birds, there were also
-great blue herons
-wood storks (nesting too far to get photos of the nests, but could get photos of the birds themselves as they visited the other shore)
-one pair of cattle egrets
-gallinules
It was just incredible to spend a few hours there watching the Great Egrets greet each other and add to their nests, or feed chicks, or turn their eggs. Some of the birds have very interesting vocalizations, too.
You do have to pay for admission like a regular tourist. They apparently also have extended hours for photographers. We didn't go then but we had no trouble getting some lovely photos.
http://www.gatorland.com/tours_birding_pass.shtmlAs I said it's an odd place to bird, and I felt a bit uneasy about seeing birds eating hotdogs, but then in Florida the birds are eating weird stuff everywhere: I saw huge flocks of Coots eating popcorn in Disney, and Ibises eating junk food in Epcot.
You may find birding opportunities unexpectedly, too. We had wild turkeys in our parking lot every morning because our hotel backed onto a planted pine grove green space.
