Abstract
Previous studies have shown that the threat level posed by a predator can vary with physical features. In this study, we tested whether the wing posture of a raptor could serve as a clue for bird threat assessment. We observed the behavioral response of Japanese tits Parus minor to taxidermy dummies Eurasian sparrowhawks Accipiter nisus with either spread wings and closed wings. The results showed that the response scores to sparrowhawks with spread wings were higher than those to sparrowhawks with closed wings. We suggested that Japanese tits can assess the predation risk associated with changes in wing posture of predators.