Figure 3. Responses of Japanese great tits to playbacks of ABC, D and ABC–D calls, and background noise (BN).

(a) Number of horizontal scans made by tits in 90 s (generalized linear mixed model: χ²=62.58, df=3, P<0.001). (b) Percentage of trials in which tits approached within 2 m of the loudspeaker (generalized linear mixed model: χ²=34.56, df=2, P<0.001). The box and whisker plots display the median value and 25 and 75% quartiles; the whiskers are extended to the most extreme value inside the 1.5-fold interquartile range. Sample size: n=21 individuals. Each individual was exposed to all four treatments in varied orders, giving n=21 samples per treatment.