Bird strike

We found this on our garden room window on our return from holiday.  I've been meaning to get a photo.  As you can see from the other debris, it's a while since our window cleaner visited.  He came sometime whilst we were away, because he left his card.

From the size, I think this was probably a pigeon.  There's no sign of a bird or feathers under it, so hopefully it survived the impact.

I've only seen one of these bird marks before, when I lived in North Norfolk, which from the shape was clearly an owl.