Do pied flycatchers use personal or social information for replacement clutch decisions? A field experiment

Life is a continuous stream of decisions: organisms are repeatedly confronted with multiple options from which to choose. To make the best decisions and maximise their fitness, individuals need to collect information: from direct interactions with the environment (personal information) or from observing other individuals interacting with the environment (social information). Yet, very little is known about the details of decision-making by animals in their natural environments, including the sources of information they use in the process. We set out to determine the relative importance of social and personal information in breeding habitat decisions in the migratory pied flycatcher, Ficedula hypoleuca. In a field experiment in Finland, we manipulated flycatcher breeding success and then allowed individuals to choose among breeding sites labelled with artificial cues (arbitrary symbols) associated with their own (manipulated) and neighbour's reproductive success, respectively, for laying a replacement clutch. Birds did not appear to distinguish among the symbols representing their own, their neighbour's or a neutral symbol, indicating that they did not use either information source when deciding about a replacement clutch. Also, the choice did not influence subsequent investment into breeding (clutch size). This may suggest that pied flycatchers utilise other cues (e.g. breeding success or predation risk on larger scales) when having to make a decision about replacement clutches. We discuss our results in light of constraints imposed by a short breeding season of migratory birds.