Thread: What is this skull from ?

Is it a mammal, a bird (plane) or what ?
Where could I find out for sure ?







There were just a couple of fine ribs around and one vertebra but no jawbones, feet or beaks.
It was on top of the leaf litter, in tall old manuka forest among Waikato farmland.
My theory is it was a harrier hawk (Circus approximans).