Seemed to be BOOBOOKS? answering each other while I was taking photos of an Aurora.
One seemed to be a km or so away to the west and the other was about 1km away towards the East.
I was facing due South for the Aurora.
They were there for >20 minutes at 23:10 hrs
Flying out of a stand of trees along the Port River Expressway, then soaring for a while and stooping suddenly from a great height at a Feral Pigeon. It narrowly missed its target.