Wiley, R. H.   2005.   Individuality in songs of Acadian flycatchers and recognition of neighbors.   Animal Behaviour   70:   237-247.


Acadian flycatchers, Empidonax virescens, like many other tyrant flycatchers (Tyrannidae), sing complex songs with little variation among individuals. Careful measurements of frequency and timing revealed that individuals' songs included consistent but slight individual differences.

A comparison of differences between songs of territorial neighbors and between more distant males revealed no indications that these birds learn even minor modifications of their songs.

Playbacks of neighbors' and strangers' songs for 30 min at standardized distances from singing subjects provided evidence that territorial birds recognize these differences. Playbacks for only 2 min provided no such

evidence, although similar experiments with hooded warblers, Wilsonia citrina, and Kentucky warblers, Oporornis formosa, in the same forest had provided strong evidence for neighbor-stranger discrimination.

The slight differences in individuals' songs and the degradation of songs during propagation in a forest must make this discrimination difficult for Acadian flycatchers.

In tyrant flycatchers, complex songs with innate developmental constraints might evolve by sexual selection for species recognition despite disadvantages for individual recognition.

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