Figure 1

The symbol preferences of the collared flycatcher and the great tit over elapsing time. Fitted regression curves (thick lines) for each of the three symbols and their 95% highest posterior density credibility intervals (thin lines) in relation to the day of symbol choice for both collared flycatchers (left) and great tits (right). The horizontal dashed line indicates a probability of 1/3, which is expected if symbol choice is random.