{"fact":"Wild American crows can recognize and remember the faces of threatening people for at least 2.7 years, even if those people are in crowds or have changed their clothes.","context":"Here we demonstrate experimentally that a cognitively advanced, social bird, the American crow, Corvus brachyrhynchos, quickly and accurately learns to recognize the face of a dangerous person and continues to do so for at least 2.7 years... crows consistently used harsh vocalizations to scold and mob people of different sizes, ages, genders and walking gaits who wore the dangerous mask, even when they were in crowds.","source":"John M. Marzluff; Jeff Walls; Heather N. Cornell; John C. Withey; David P. Craig, Lasting recognition of threatening people by wild American crows, 10.1016/j.anbehav.2009.12.022","index":22}