Fledgling calls are a source of social information for conspecific, but not heterospecific, songbird territory selection

The choice of breeding territory can strongly affect an individual's fitness. Individuals can use information obtained from social cues emitted by other organisms to assess territory quality when making settlement decisions. Social information sourced from cues indicating the current inhabitants' reproductive success (i.e., performance-based cues) can be especially valuable as such cues may directly reveal territory quality. We tested social information use in a songbird system using experimental playbacks of Veery (Catharus fuscescens) fledgling calls (evidence of prior nest success) during the postbreeding season. We demonstrated that with year effects considered, Veeries used performance-based social information available during the postbreeding season to select sites for territory establishment in the following year. During the first year of the study, Veeries occupied a greater proportion of plots with experimental broadcast of fledgling calls relative to control plots, whereas Ovenbirds (Seiurus aurocapilla), a coexisting heterospecific ground-nesting species, did not. Fledgling call treatments did not have carryover effects that influenced Veery settlement decisions during the second year of the study. Ovenbird abundance varied with treatment combinations between years, but evidence indicating a carryover effect was limited. Our results indicate that postbreeding social information may vary among years for both conspecifics and heterospecifics, therefore highlighting the importance of considering year effects in studies on social information use.