The Great Horned Owl (Bubo virginianus) is considered a crepuscular and nocturnal predator that preys primarily on small mammals (Cromrich et al. 2002). It is an opportunistic feeder, however, and has a diet broader than that of any other North American owl (Marti and Kochert 1996). There is extensive indirect evidence (pellets, prey remains, etc.) that the Great Horned also hunts diurnally (Earhart and Johnson 1970, Jaksic et al. 1981, Bosakowski et al. 1989, Bogiatto et al. 2003, Ganey and Bloch 2005). However, direct observations of this behavior are rare, and how often Great Horned Owls actually hunt during the day is unknown. Owls’ use of sound to detect prey in the dark is also well documented (Payne 1971, Konishi 1973, Marti 1974), but the use of audio detection by Great Horned Owls during the day has not been reported. In this paper, we describe our observation of a Great Horned Owl attempting to take a distressed American Robin (Turdus migratorius) during daylight hours.