Shark Valley's wildlife is seasonal in a very literal way, because it follows the water.
Dry season, roughly December to April. The prairie drains, the canal beside the road holds on to water, and everything comes to the canal. Alligators lie on the bank in numbers that genuinely startle first-time visitors. Wading birds — great blue and tricoloured herons, great and snowy egrets, wood storks, roseate spoonbills if you are lucky — work the edges. Anhinga, cormorant, and in the right years large numbers of white ibis. Soft-shell and cooter turtles haul out to bask.
Wet season, roughly May to October. Water spreads back across the whole prairie and the animals spread with it. You will still see alligators, just fewer and further off. The compensations are afternoon thunderheads that make photographs, green sawgrass instead of straw, and far fewer people.
Two things you should know rather than learn the hard way. Alligators on the verge are wild and unmanaged; the park's guidance of staying well back exists because people have been bitten here. And the mosquitoes from June onward are serious enough that a bike ride without repellent is a mistake.