Dear-enemy effect between two sympatric bird species

In this study I investigated the occurrence of the dear-enemy effect in territorial interactions between two non-passerine bird species: water rail (Rallus aquaticus) and little crake (Zapornia parva). I used a cross-species playback experiment where water rails received calls of strangers and neighbouring little crakes, while little crakes received calls of water rails in the same manner. In addition, each focal pair was exposed to control calls of little grebes (Tachybaptus ruficollis). During the treatments, it did happen that either a neighbour of another species imitated by us or an individual of the same species called from adjacent territories. However, since each pair received a long series of playbacks, we could isolate responses to such unexpected events from responses to playbacks. If an additional bird responded during the procedure, we only considered the reactions up to that point for all three treatments with a given pair. Data included in the database (approaches, time near speaker, total number of calls) present, therefore, such isolated responses that were later analysed. See article "Dear-enemy effect between two sympatric bird species" for more details.