An example is when Ralph assembles a group of hunters to go and find food. To do this they have to make weapons to kill the animals that are their food source and have to make these weapons from complete scratch. This shows that they know how to make weapons when in a survival situation.
Another example of survival skills is when they make a fire for warmth and other uses. As well another use they used the fire for is as a signal, so when any possible rescuer comes by the can attract them by using the fire as a signal.
The last but not