I sent out several catching expeditions recently, and it didn't register until now that my reports tell me of only one catcher at any one place, even though I sent out three. I'm bad at explaining, so have a screenshot.

But this is what it says:

There's no one at Big Field.
Your catcher saw how a Dragon flew from the Big Field to Creek.
Your Bird catcher was attacked by a Dragon at the Creek. Fortunately, no one was hurt.
There's no one at Magic Glade.

I sent out three Bird catchers. I'm not sure if this is a bug or it's just me not understanding how this works.

SeaCrest, the log is telling you about 3 catchers, not one. They were sent to Big Field, Creek and Magic Glade. Big Field and Magic Glade were empty at this cycle, but the catcher on the Creek met a Dragon who was hunting at the Big Field on the previous cycle. Any of your catchers met a Bird class pet (Roc or Gryphon) to try to catch it.