The swamp harrier (Circus approximans), also known as the Australasian marsh harrier, Australasian harrier, kāhu, swamp-hawk or New Zealand hawk, is a large, slim bird of prey widely distributed across Australasia. It is one of the few birds to have benefited from European settlement of New Zealand: It is a bird of open country and became firmly established in New Zealand after forests were cleared by Polynesians.