Meeting Abstract
Research on cawing in American crows (Corvus brachyrhynchos) has often assessed the acoustic variation of isolated caw syllables emitted by individual crows. However, crows often emit syllables in bursts (i.e., multisyllabic calls) and sometimes call collectively in groups. How collective cawing may vary by context has not been well explored. In this study, we 1) examined the context-dependency of group calling in two aggregation types – mobbing and pre-roosting aggregations and 2) used playback of natural sounding crow call sequences to examine the function of pauses (i.e., the silence between successive calls) in crow vocal communication. We observed that, while controlling for the number of calls, average pause durations were significantly shorter during mobbing vs. in pre-roosting aggregations. Based on this finding, we combined recorded calls to create three different playback files where pause durations were randomized, accelerated, or decelerated, and played these files to crows on diurnal foraging areas. Decelerated playback led to significantly fewer movements towards the playback speaker and fewer crows within 30 m of the speaker compared to the randomized playback. Crows also did not as closely approach the speaker in response to decelerated vs. randomized playback. Post hoc tests did not reveal behavioral differences in response to accelerated vs. randomized or decelerated playbacks. These findings suggest that crows both alter collective calling across different contexts and use collective cues when responding to group calling.
