Bob,
It is entirely possible that there have been snakes in my vicinity all along, but as you said they blend in and I just never saw or heard them. But as the rattler let me know he was there because he could sense my footsteps I would think that any others would also have done the same.
As I recall, the main culprit in the Everglades infestation, is the Burmese Python. It can top out at about 18 ft. (5.5 m). I have seen photos of one after ingesting an alligator, the only real natural competitor in the swamp. All other predators in the swamp are on the decline as a result of loss of food supply and becoming food themselves.
I've read that in 1992 hurricane Andrew demolished a python breeder/zoo facility in Florida and resulted in the release of the viable population we are seeing at this time.
At one point a contest for size and number of snakes captured or killed was started to try to hold the population down. We'll see if it has any effect. The ecology of the Everglades has been drastically altered. The effects of the exotic pet trade at it's worst.
eyesup