For birds also....in the Sanibel area check out Little Estero Lagoon. A bit north (near Tampa) is Ft. DeSoto State Park ($5 entry fee)....awesome for birds and a great beach too.

A bit west of Orlando near Lakeland is the Circle B Bar Preserve .... 1500 acre wildlife preserve with very nice walking trails .... gators and birds galore. Lots of trees with spanish moss along the trails, really beatiful. The trails are 1 to 3 miles long. No entry fee.