That is one adorable bird. Are the traps in place because the cats go after the Teals?
I think so. Everywhere I've been in NZ (as far as wilderness or near-wilderness) I've seen traps for non-native mammals like rats, possums, and cats (not for sheep, cows, and llamas, though).
The feral cats on Great Barrier are very destructive on the birdlife. If this one was on the walk to Mt Hirakimata (Hobson) it was protecting black petrel nests. We don't have possums or mustelids on the island.