- di-urnal (active in the day)
- crepuscular (active at dawn and dusk)
- and nocturnal (active at night)
The eye color of owls is a good clue to this-
- Yellow eyes like the sun for di-urnal owls (short-eared owl and little owl)
- Orange eyes like the sunset for crepuscular owls (long-eared owl)
- Dark eyes like the night for nocturnal owls (tawny owl)
- The species that throws this is the barn owl, which has dark eyes but is actually crepuscular in the UK but in the US is nocturnal, but the system works with most species around the world.