Song bout length is indicative of spatial learning in European starlings

Female songbirds are attracted to male song, and song may honestly signal male quality. Song is a phenotypic expression of a complex learned behavior and therefore could be indicative of other cognitive abilities. Stressful conditions during early development are known to adversely affect the development of the mammalian and avian brain, and recent evidence suggests a positive association between song quality and learning ability. However, prior studies have not assessed how early-life stress affects both general cognitive functioning and song learning. We subjected nestling- and juvenile-caught European starlings (Sturnus vulgaris) to either an ad libitum or food-restricted diet until approximately 90 days of age. As adults, birds’ cognitive abilities were assessed via spatial foraging and social learning tasks, while controlling for the effects of neophobia. Song learning was assessed in undirected and directed singing contexts. We found that birds fed the ad libitum diet had significantly longer song bouts in both singing contexts, made fewer errors in the spatial foraging task, but performed worse on the social learning task than food-restricted birds. Overall, song performance only correlated with performance on the spatial foraging task: Males with longer mean song bouts in the directed singing context committed fewer errors. These data suggest that the neural structures supporting song and spatial abilities are both affected by nutritional stress during development. Female starlings are attracted to longer song bouts and may thus use song bout length to infer spatial learning abilities of potential mates.