Because there are certain ones you haven't encountered, I'm assuming? I'm not familiar with the exact terminology here, but "region" may include more than your local map.
My wording on that was bad, sorry. I was wondering more why like, my region-pops list shows Giant Tigers at 1, while region-pops list-all had about...18, I think it was?
If I recall correctly, region-pops looks at a DF structure of flora/fauna spanning a 7*7 world tile area with your fortress in the middle. This also explains why you can get stuff like ocean creatures reported even though you're not embarked particularly close to the ocean.
Determining what the technical difference is between the reports requires a study of the script, though.
This though would make sense...it'd be everything in the surrounding area, which miiiight end up showing up sometime? Hm. That helps make me less confused, thanks.
EDIT: Not sure if this is place to make a suggestion or not, but would it be possible to add a confirmation of the script being on or off to warn-stuck-trees and warn-starving? I assume it's on to begin with, but it'd make it easier to tell.