Producing and preferring appropriate sexual traits is essential for individuals to acquire compatiblemates, yet the process is challenging when traits and associated preferences are learned. Juvenilesongbirds learn their songs by imitating adult conspecifics, with early experience shaping their vocaldevelopment. While juveniles in many species primarily imitate unrelated conspecifics, the role of thesocial father in priming nestlings for song learning by influencing early song responses remains lessunderstood. The pied flycatcher (Ficedula hypoleuca) is a long-distance migrant passerine bird whosenestlings are known to discriminate songs from other populations and species. To investigate whetherthis discrimination extends to individual recognition, we compared the responses of 13-day-oldnestlings to playback of their social father’s songs versus songs from an unfamiliar male of the samepopulation. We show that nestlings produce more high intensity begging calls in response to theirsocial fathers’ songs. This implies that pied flycatcher nestlings can recognize conspecific songs at theindividual level. Our study highlights the role of parental inheritance in shaping song learning andcontributing to cultural evolution in songbirds.

Song learning in songbirds is a critical process for sexual selection and cultural evolution, with earlysensory learning guiding later song production and preferences. In pied flycatcher (Ficedulahypoleuca), males produce long, complex songs before pairing and shift to simpler, shorter songsduring the nestling stage, potentially providing early auditory input for nestlings. While nestlings havebeen shown to discriminate conspecific songs, local dialects, and even their social fathers’ complexsongs at an early age, their responses to these familiar simplified songs versus unfamiliar complexsongs remain unknown. Nestlings may exhibit a stronger response to shorter songs either becausethese are the songs they commonly hear or because they are inherently easier to process andrecognize. We conducted playback experiments presenting nestlings with both simplified and complexsongs from the same male. Our results revealed that nestlings responded more actively, withincreased postural begging behaviors, to shorter songs than to longer songs, a preference thatpersisted regardless of prior exposure. These findings suggest that both early auditory experience andinherent acoustic salience contribute to song recognition and learning, highlighting the role of earlysong exposure in shaping vocal development.

Learned sexual signals and preferences play important roles in sexual selection, but for learning to be adaptive, young animals must attend to and learn from appropriate models. Song learning in oscine songbirds offers a well-studied system for examining the mechanisms underlying such selective learning, including whether early biases toward relevant song models reflect inherited predispositions or early auditory experience. In pied flycatchers (Ficedula hypoleuca), nestlings have previously been shown to respond more strongly to their father’s song than to stranger song, while begging responses are also strongly influenced by nestling condition. Here, we tested whether such early recognition of father’s song reflects inherited predispositions or early auditory experience using an embryonic cross-fostering experiment in the wild. Nestlings were reared either by their genetic parents or by foster parents and were later exposed to playback of songs from their social father, their genetic father, and an unfamiliar local male. Nestlings in our experiment did not show differential begging responses to the three song treatments, in contrast to the stronger responses to paternal than stranger song previously detected in the same population. The interaction between song treatment and offspring status was therefore uninformative for distinguishing between experience-based and inherited mechanisms. Heavier nestlings showed reduced postural begging, suggesting that low motivation constrained behavioural expression. Our results suggest that begging-based playback assays may underestimate early auditory discrimination when nestlings are in good condition. The present data therefore remain inconclusive about whether early father-song recognition is shaped primarily by auditory experience, inherited predispositions, or their interaction.

Sexual selection has produced diverse male ornaments and signals, yet understanding why females prefer particular traits and what benefits they gain from those preferences remains a central challenge in evolutionary biology. Song complexity is one such trait widely linked to female preference in songbirds, and has been hypothesized to signal cognitive ability, a latent quality difficult for females to assess directly. We tested this hypothesis in wild pied flycatchers by measuring associations between four song complexity variables and performance on a novel foraging task and a detour reaching task in breeding males. Contrary to our prediction, repertoire size and syllable switching rate, the song complexity measures most consistently linked to female preference in this species, both negatively predicted success on a novel foraging task. Within-individual variability in versatility, a previously unstudied song trait, positively predicted detour reaching success. No other song complexity variable predicted cognitive performance after correction for multiple comparisons, and cognitive performance showed no consistent cross-task associations. Overall, our findings suggest that the song measures females attend to in pied flycatchers do not reliably signal cognitive ability, and that female preference for complex song is more likely maintained through its role as a multicomponent honest signal of overall male quality.