There are sixteen species of harriers in the world and the kāhu is the largest of them. Maori believed the kāhu was a noble bird, a chief amongst birds.
Kāhu (swamp harrier or harrier hawk) are often seen as they soar on air currents above open countryside, eyes scanning the air and ground below them for food. They will feed on road kill as well as catching insects, small birds and animals. In winter they add rabbits and possums to their diets when other more easily caught food sources are scarce. They have long legs and feet with sharp talons so they can grab their prey without having to land. Magpies and spur winged plovers are their enemies and they are often chased and attacked by these species.
Kāhu sometimes nest in trees but more usually on the ground in flax, raupo or bracken. The nests are a raised platform of sticks and branches woven loosely and lined with grass.
They are not threatened and are partially protected. Birds which attack lambs, chickens or other stock may be shot. Kāhu (swamp harrier) and kārearea (NZ falcon) are easily confused.