Mobbing sequences of American wrens elicit mobbing responses in European tits

Recent studies showed that some species of birds can combine two distinct calls (alert and recruitment calls) into a mobbing sequence that triggers mobbing behaviour in conspecifics and heterospecifics. Interestingly, some bird species also react appropriately to the mobbing sequences of allopatric species. Great tits, Parus major, are known to react appropriately to the mobbing sequences of allopatric chickadees. This study investigated whether great tits appropriately responded to the mobbing sequences of an allopatric non-Paridae species, namely, the Carolina wren, Thryothorus ludovicianus, a North American species producing similar mobbing sequences to great tits. The reaction of great tits to the mobbing sequences (alert + recruitment calls) and recruitment calls of Carolina wrens was compared. Results indicated that recruitment calls and mobbing sequences triggered a similar approach in receivers. In addition, the probability of displaying wing flicking was significantly higher during the playback of mobbing sequences than during the playback of controls and recruitment calls, indicating that they appropriately respond to the mobbing sequences given by an allopatric non-Paridae species and their isolated parts.