Research, and I'm not saying sit down and write a Doctoral thesis. It's pretty common knowledge that Gators inhabit Florida swamp land.
The problem with people and animals, is the people. It's cute to want to feed the birds. But then fish eat what the birds don't get, other bigger animals that eat those fish and birds follow them, etc... There are reasons that signs are posted saying to NOT feed the animals.
What was completely wrong was for Disney to go killing off a bunch of gators they found in the lagoon after that. Because someone let their kid thrash around in the water at dusk (thereby making it seem to a predatory animal that they were an injured meal), and the gator did its animal thing, a bunch of other gators died for no reason other than they were just in the lake. Also, a bunch of other knee jerk reactions were instituted in the parks as well (besides the fences and signs).