Figure 2.

Vocal behaviour by each dyad during the cooperative task trials. The relationship between whistle absence (blue bars) and presence (red bars) and the mean time between button presses with standard errors for the male dyad (a) and female dyad (b) in trials where both animals pressed their button. Sample size (N) represents the number of trials per dyad with or without whistles. The horizontal line at 1 s represents the cut-off for a successful trial. The number of whistles (in trials with at least one whistle) for unsuccessful (blue dots) and successful trials (red dots) for the male dyad (c) and female dyad (d). Asterisks denote statistical significance (***p < 0.001, **0.001 < p < 0.01, *0.01 < p < 0.05).