Usually Xavier brings the prey to Diamond as evidence of his ability to provide for the family. Sometimes he is reluctant to hand it over – and conversely, sometimes she rejects it (notably starlings!).
In this case, Xavier carries the prey past the box, but doesn’t land. It’s a good sized prey, possibly a pigeon. She gives chase and, although just out of sight, we know he transfers it to her as he returns shortly afterwards empty handed.
The clip was recorded at one quarter speed from the ledge cam.