Sobre la historia de los cantos de las aves o los cantos de las aves como historia / About the history of the songs of birds or the songs of birds as history

Resumen Igual que es posible trazar una historia de los cantos de las aves, de su recepción por y su relación con los seres humanos, también se puede especular sobre si esos cantos pueden funcionar como historia, viva, sonora, en qué grado y modos, así como en qué diferiría esa historia aviar de la humana o si podría enriquecerla. Muchas aves, después de todo, transmiten y aprenden sus cantos unas de otras, construyen sobre ellos y los complican, recogiendo otros sonidos que asumen e incorporan, sonidos humanos incluidos. Crean así paisajes sonoros que no siempre quedan de fondo: en ocasiones, reclaman su relevancia y toman el primer plano, en la historia y como historia.

Abstract Just as it is possible to trace a history of the songs of birds, of their reception by human beings, and of how humans relate to them, it is also possible to speculate on whether these songs can function as history, a living, resounding history, to which degree and in which ways. As well as on how that avian story would differ from the human one, or if it could enrich it. Many birds, after all, learn their songs from each other, they build on and complicate them, picking up other sounds they incorporate, human sounds included. Thus, they create soundscapes that are not always in the background: sometimes, they claim their relevance and take the foreground, in history and as history.

Collective decision making and social interaction rules in mixed-species flocks of songbirds.

Associations in mixed-species foraging groups are common in animals, yet have rarely been explored in the context of collective behaviour. Despite many investigations into the social and ecological conditions under which individuals should form groups, we still know little about the specific behavioural rules that individuals adopt in these contexts, or whether these can be generalized to heterospecifics. Here, we studied collective behaviour in flocks in a community of five species of woodland passerine birds. We adopted an automated data collection protocol, involving visits by RFID-tagged birds to feeding stations equipped with antennae, over two winters, recording 91 576 feeding events by 1904 individuals. We demonstrated highly synchronized feeding behaviour within patches, with birds moving towards areas of the patch with the largest proportion of the flock. Using a model of collective decision making, we then explored the underlying decision rule birds may be using when foraging in mixed-species flocks. The model tested whether birds used a different decision rule for conspecifics and heterospecifics, and whether the rules used by individuals of different species varied. We found that species differed in their response to the distribution of conspecifics and heterospecifics across foraging patches. However, simulating decisions using the different rules, which reproduced our data well, suggested that the outcome of using different decision rules by each species resulted in qualitatively similar overall patterns of movement. It is possible that the decision rules each species uses may be adjusted to variation in mean species abundance in order for individuals to maintain the same overall flock-level response. This is likely to be important for maintaining coordinated behaviour across species, and to result in quick and adaptive flock responses to food resources that are patchily distributed in space and time.