"Swink" will most likely mean crouch because since the excerpt says: "The gators "swink" close down but it don't do them no good. They got to move." So it should be said: "The gators crouch close down but it don't do them no good. They got to move."
If you used the other words and replaced swink with them, they would make no sense. So once again, the answer is "crouch"
I hope this helps! :)