Dark-slate grey all-over, they have a heavier bill & shorter legs than the (now) more often-seen white-faced heron.
Crouching low they stalk for food. Walking smoothly, sometimes running, hunting from one end of the pool to the other.
Necks drawn in. Waiting. Jabbing. Lunging. Spearing small fish, crabs, molluscs…
With a slow flapping of wings, flying just above water, they go to their nests. In caves, crevices, rock shelves, flax bushes, & pohutuakwa roots.
Matuku moana is a warm waterbird, living from Eastern Asia to Australia to Aotearoa/New Zealand. Here is their southern-most limit, and here they are preyed upon by stoat, ferret, and cat.