He's made that honking sound before, but usually not for as long as today. I've always associated it with disappointment, or perhaps frustration when his best intentions (like a gift of prey) are not met with enthusiasm.
The only times I recall Di accepting a starling from X is when she has chicks to feed. Also, the Sydney sea eagles honk like that but I've never heard a falcon honk. X, you are one of a kind--lol.
Could he be mimicking some sound he heard somewhere, like crows and magpies do? A cold car engine trying to start up? It sounded like a mechanical noise to me.
Okay, I get it, you don't like Starlings... Just don't expect champagne and caviar on a Vegemite on toast or meat pie & beer budget. Don't like that then you go out and get dinner yourself, perhaps then I might get to spend some quality father time with the kids.