Discrimination of song types by male great tits

The purposes of this study were: to test whether male song birds could be trained to discriminate between a reference song type and a set of other types and to see if in learning the discrimination the birds had formed a category of "reference song" as opposed to "others". Three male great tits learned to discriminate between a reference song type (B) and 10 others. All of them showed an improvement with experience, although the final scores and consistency varied between individuals. In spite of the variability among birds some of the 10 song types were easier to discriminate from B than others. Two of the birds achieved at least 80% of discrimination, but only one of them yielded good data in the following categorization tests: In one session the bird was presented with 20 novel "other" song types and the same reference type B. This bird treated all 20 types as "others". Therefore, the bird appears to have formed the category "other". In two other sessions the bird was presented with 40 different versions of B (as classified by the authors) recorded from 40 different individual birds, and the same 10 training "others". The bird categorized 16 out of the 40 Bs as B, and overall discriminated significantly between Bs and the 10 other types. Therefore, this bird generalized the stimulus song B to other related stimuli. We conclude that, although our results are preliminary, they at least indicate a method of studying how birds categorize songs.