{"fact":"Crows living in areas where they are persecuted by humans are more cautious and less aggressive towards people, even those wearing a dangerous mask.","context":"Risky, aggressive scolding by crows was sensitive to variable costs across study sites; aggression was less where people persecuted crows most... Increased caution and reduced aggression in persecuted corvid populations are well known (Knight 1984; Knight et al. 1987).","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":26}