A Conversation Between Two Falcons?

A lot of activity last night in the Falcon community. In this video you will see Fiona on the ledge and then another Falcon fly up. There are some vocalizations, which to the lay person seem like a warning to come no further. Perhaps she’s guarding these stone pebbles she seems to eat because she takes a few nibbles. (Periodically she does eat here, but there is currently no food on the ledge. Sooner or later there will be food brought back the ledge, so stay tuned.) Continued vocalizations occur and then Fiona sits before flying away.

I’ve also heard similar vocalizations during the day, but this usually occurs when she first lands on the ledge. The tenor and tone of those vocalizations are different than the ones heard on this video, which clearly have a warning tone to them.