They say that the color of the eyes of the owl gives indication of when the owl hunts :
Yellowish : during daytime (diurnal)
Dark : night time (nocturnal)
Orange : dusk/dawn (crepuscular) or daytime
Having taken the time to check the facts, there is no real correlation between hunting time & iris color.
All dark eyed owls will hunt nocturnally with a few having crepuscular and/or diurnal habits. With the exception of one (1) diurnal hunting owl with orange eyes, the rest are strictly nocturnal or nocturnal & crepuscular.
Yellow eyed owls have the most wide spread hunting habits, some being either strictly nocturnal, crepuscular or diurnal and others with various combinations of preference.
Information sited by: Owls introduction
This footage is from the Arizona-Sonora Desert Museum’s Raptor Free Flight Program.