Those traps are actually stoat traps. Too small for a possum. That area there at the port (and a lot of the shore line) is home to a few penguins that live in the holes in the ground at night. The stoats like to eat the eggs so we catch them to help the penguins.
Also the driftwood piles are like a fun beach activity that a lot of people just do when there are a lot of large drift wood. I myself have probably made more than I can count in my time.
I am loving your posts!