Figure 2.

Sound spectrograms of some of the oriantha and nuttalli songs used as stimuli. In discrimination trials, nuttalli dialect N1 (for example) was used as a habituation stimulus, and either nuttalli dialect N2 or Ns was the dishabituation stimulus. Ns was a synthetic hybrid song created by replacing the complex syllables of N1 with those of N2. N1, N2, oriantha dialect O1, and O2 were used as habituation stimuli in both tests 1 and 2, and different versions of Ns and Os were synthesized depending on which song was used as the habituation stimulus. Ten pairs of natural nuttalli and oriantha dialects were used for different birds.