Does bib size act as a status badge in territorial Reed Buntings (Emberiza schoeniclus)?

Rubolini D., Boto A. & Bogliani G.



Abstract:

The hypothesis that bib size acts as a signal of status was tested on territorial Reed Bunting males. In accordance with previous results, we predicted that if males display their status through bib size, a territory invasion by a large badge model would elicit a more aggressive response from the territorial individual. This was tested by presenting two stuffed models with the extremes of badge variation (smallest and largest, as found on 26 museum specimens) to territorial males of unknown badge size and by observing and comparing the responses. A third model, a male in winter plumage, was used as a control. Our hypothesis was not confirmed, but there was a tendency in the predicted direction: territorial males were more aggresive towards the large badge model even if not significantly so. Bib size may then play a minor role in honest signalling in the Reed Bunting, and other cues such as song structure and/or song rate might be more important. It must also be stressed that bib size variability could be involved in individual recognition.