Breeding habitat choice and investment decisions are key contributors to fitness in animals. Density of individuals is a well-known cue of habitat quality used for future breeding decisions, but accuracy of density cues decreases as individuals disperse from breeding sites. Used nests remain an available information source also after breeding season, but whether such information is used for breeding decisions is less well known. We experimentally investigated whether migratory, cavity-nesting pied flycatchers (Ficedula hypoleuca) prospect potential breeding sites after breeding season and use old nests as a cue for future breeding decisions. In late summer 2013, forest sites were assigned to four treatments: (1) sites including nest boxes with old nests of heterospecifics (tits), (2) sites including suitable but empty nest boxes, (3) sites with unsuitable nest boxes, or (4) sites without any nest boxes. In the following year, we investigated pied flycatcher habitat choice and reproductive investment according to these “past” cues while also controlling for additional information sources present during settlement. Flycatchers preferred sites where tits had been perceived to breed in the previous year, but only if great tits were also currently breeding in the site and had a relatively high number of eggs. Old flycatchers avoided sites previously treated with suitable but empty cavities, whereas young flycatchers preferred sites where tits had apparently bred in the previous year. Also egg mass, but not clutch size or clutch mass, was affected by the combination of past treatment information and current tit abundance.

Data set from an experiment in natural environment manipulating the availability of social information and breeding sites for a passerine bird, the pied flycatcher Ficedula hypoleuca. Experimental manipulation was conducted during the post-breeding season (period from chick fledging to autumn migration) in 2013 and the responses were observed during the next breeding season in 2014. The uploaded files include data for nest site (nest box) occupation analysis (edited for Cox regression) and data for timing of breeding (laying date of the first egg), reproductive investment (clutch size, mean egg mass, clutch mass) and success (brood size, fledgling number). For further details, please contact the authors.