Thinking chickens: a review of cognition, emotion, and behavior in the domestic chicken PMC They have acoustically distinct alarm calls corresponding to three different types of predators, each of which requires a different type of response on the part of the receivers (Cheney and Seyfarth 1990; Seyfarth et al. 1980; Struhsaker 1967). Several species of birds also engage in referential communication, including ravens (Bugnyar et al. 2001) and chickadees (Templeton et al. 2005), among others. Another component of a sense