What clues from the story reveal that Rainsford has survival skills? Why is this fact important?

Rainsford knows how to limit his tracks as well as make all types of cool traps for Zaroff. There is the "Maylay man catcher", "the Burmese tiger pit" ( I love these names!), and some other tree spring thing. I think the tiger pit is a big hole with spikes in it. The Man catcher has a trigger where the man steps on and is scooped up and killed.The tree spike involved tying his knife to a sapling. Rainsford ties the sapling back with some vine. When it is triggered, it hits and kills poor Ivan, Zaroff’s "deaf and dumb" servant.