Checking for "Ground mounts are not allowed here"?

[LudiusMaximus]

I just realised that when moving close to "Great-father Winter" you get dismounted automatically and trying to mount again brings up "Ground mounts are not allowed here".

Is there any way of checking if the player is in such an area? I mean like IsIndoors() but for these kinds of other areas in which you cannot be mounted?

Thanks!