Looks like it's fallen off one of the roofs, it happened last year and we had to be careful when leaving the house as the parents would swoop at us.
The parents have already chased off next doods cat, swooped at a neighbour as he walked to his car and nearly crashed into front door while chasing dd1. Have phoned a rescue as it is so young but if they can't help we're probably in for a few weeks of this until it learns to fly or a cat unfortunately gets it.