The cognitive abilities of animals continue to fascinate both scientists and nonscientists. Although the abilities of the primates, our closest living relatives, generally attract most interest, several different lines of research have demonstrated high levels of intellectual capacity in birds, particularly corvids. The members of this family are known for their large brains and have performed well in many cognitive tasks using different paradigms (1⇓–3). This finding has led to substantial revision of thinking about avian intelligence, including the suggestion of convergence in the evolution of cognitive abilities between corvids and primates (4). In PNAS, Ostojić et al. (5) add significantly to this literature with a very elegant experiment demonstrating the ability of male European jays (Garrulus glandarius) to predict the feeding preferences of their mates. The study is significant for many reasons: it demonstrates a high and unexpected level of flexibility, reports results bearing strong resemblance to human state-attribution and further confirms the importance of studying cooperative as well as competitive situations.
Ostojić et al. (5) take advantage of natural courtship feeding during which a male selects food to feed his mate, raising the possibility that his choices reflect the male’s estimate of the female’s motivational state. This approach is especially interesting because female preferences change with experience, thus requiring the male to track changes in his mate’s preferences. A phenomenon known as “the specific satiety effect” allowed development of a method to manipulate female preferences.
In cases of specific satiety, recent experience eating a specific food induces a reduction in the attractiveness of that food, an effect that occurs in animals (6) and humans (7). In their first experiment, Ostojić et al. (5) determined whether European jays show specific satiety effects (figure 1A of ref. 5). The results show that prefeeding on either wax …
↵1E-mail: akamil{at}unl.edu.
