Figure 1.

Birds’ well-type preference during the test phase. Individuals are sorted from 1 to 34 according to their preference for green wells (number of foraging steps to green wells divided by the total number of foraging steps). For each bird, the numbers of test steps to green or yellow wells are shown in the corresponding colors. Asterisks above bars indicate significant color preference for yellow (birds 1–4 and birds 6–9) or green (birds 28–34).