Individual identity, song repertoire and duet function in the Crimson-breasted Shrike ( Laniarius atrococcineus )

Duets show great variety in form that can reflect different functions, such as mate guarding, mutual recognition, pair bond maintenance or territory defence. By describing the structure of duets and singing behaviour, we can investigate whether these signals are based on cooperation or conflict and which functions they might have.

Here we describe the singing behaviour and song repertoire of the Crimson-breasted Shrike in the Kalahari Desert, and assess four main hypotheses proposed for the function of duets. We found that Crimson-breasted Shrikes have a sex-specific repertoire, and the individuality of males, females and pairs is expressed acoustically. Differences in vocal strategies between the sexes indicate male mate guarding as one possible function.