Kairuku Waitaki is an amazingly docile and friendly creature, to everything but fish. Honestly, I'm not quite sure how Kairuku manages to stay populated across the island's colder climes, with the many predators stalking these frozen lands.
There is no reason to tame Kairuku for combat, since they are useless in a fight. Still, Kairuku are regularly tamed for their cuteness and friendly nature, and the fact that their bodies run extremely hot. Just standing near Kairuku can help keep a survivor warm through long, harsh nights on the icebergs.
It is weak, and has only one small defensive trait: suspended in Kairuku blubber are small, dense particles that act as a light form of armor. Adding to Kairuku's problems, a clever survivor discovered that refining Kairuku blubber (concentrating the particles in it) can yield a natural form of the same polymer utilized in advanced tribes' manufacturing processes. This has caused many tribes to hunt Kairuku extensively, a practice colloquially known as “Kairu Clubbing”.