Harrier Hawk (Kāhu) | Tangihua Ranges Northland

Circus approximans – Swamp harrier, Australasian harrier

Harrier hawks are the only New Zealand surviving native Hawk

The harrier hawk came from Australia less than 1,000 years ago but early enough to be considered native. New Zealand already had a hawk, the Eyles harrier. The Eyles harrier was about four times the size of the Australasian harrier and had adapted to forest hunting. The Eyles hawk became extinct not long after Maori arrived, when the forests were burnt and many of their prey also became extinct.
The destruction of the native forest pre European and for farm development has provided an ideal habitat for the Australasian harrier hawk and they have flourished.

Harrier hawk description

They are a brown bird commonly seen circling over head. The female is bigger than the male at 850gms. They are both 50 -58cm in length with an average wing span of between 120 – 145 cm.

Harrier hawks diet

Hawks are hunters and scavengers. Dead Possums and rabbits provide an important food source, plus they prey on small animals and birds by swooping down and grabbing them in their talons.
They will rob bird nests both in trees and on the ground.
In turn both mobs and individual birds will attack them, the most common being magpies.

Breeding

The male hawk sets up a territory in June. This is when they can be heard calling to their mates and threatening the opposition, the rest of the year they tend to be silent.
The female hawk will set up a nest in swamps on a mound. The eggs are laid in September – December, usually between 2 and seven eggs. Incubation takes between 31-34 days and is done by the female.
Both sexes raise the chicks but it is the female who feeds them. Food is passed from male to female in dramatic aerial food-passes where the female turns upside down to take prey from the male.
Not all of the eggs hatch. Of those who hatch usually only one or two survive to adulthood depending on the food supply. The young hawks are ferociously competitive for the food the female parent brings. The small weaker chicks miss out. The older stronger chicks, because they get more food grow faster, get more food, become bigger until the smaller chicks die.