Can an old rook learn new tricks? Vocal command comprehension and obedience in rooks (Corvus frugilegus)

Although many animal species are known to learn to respond to human verbal commands, this ability is understudied, as are the cues used to do so. For the best-studied species, the dog, domestication itself is used to justify successful attending to human communicative cues. However, the role of domestication in sensitivity to human cues remains debated. Corvids are songbirds that engage in complex communicative behaviors with conspecifics and with other species. Rooks (Corvus frugilegus) are a cognitively complex, undomesticated corvid shown to possess complex vocal behaviors, and to learn to follow human gaze and pointing cues. Leonidas (Leo), an adult rook, began following verbal commands during unrelated studies, and was tested to confirm his command proficiency and to examine what part(s) of the signal he was using. Leo learned to perform three verbal commands correctly, and was primarily attending to the auditory components of the commands. He showed no evidence of using gaze or any subconscious cues from the experimenter, and though he did initially attend to lip movements, he rapidly overcame their absence. Two additional rooks could only be tested for a shorter duration, but also showed learning of commands, and reached proficiency in some. The ability of this undomesticated non-mammalian species to learn human verbal commands joins existing evidence that neither domestication nor extensive enculturation are strictly necessary for use of heterospecific human cues: instead, some species may be able to co-opt other complex cognitive abilities, possibly the same ones required for their complex communication, to achieve this.