Post-breeding public information use in a ground-nesting songbird community
Organisms constantly make decisions that can strongly affect their fitness. For birds, the territory an individual chooses to breed in can have large and direct effects on their reproductive success. Birds can assess territory quality to make settlement decisions by using information obtained from social cues emitted by other organisms. Public information (PI) from performance-based social cues reveals territory quality by advertising the current inhabitants’ reproductive success. I studied PI use in the Veery (Catharus fuscescens) and its effect on avian community responses by conducting a playback experiment. I hypothesized that Veery fledgling vocalizations present during the post-breeding season are PI cues used by Veeries and other ground-nesting songbirds (i.e., Ovenbirds [Seiurus aurocapilla]) for territory establishment in subsequent breeding seasons. Moreover, I hypothesize that ground-nesters integrate multiple social cues sampled throughout the breeding season when selecting future breeding territories. To test this, I played Veery fledgling vocalizations and silent controls at plots during the post-breeding season in 2009 and 2010. I also played chipmunk vocalizations (nest predators, i.e., social cues indicating lower quality territory options) at half of these plots during the pre-breeding season. Response data (nest distances to nearest plot, nest counts at each plot, and nest initiation dates) were collected during the following breeding seasons as well as breeding songbird abundance for both ground- and canopy-nesters. My results show that both Veeries and Ovenbirds were more likely to settle in fledgling treatment plots compared to silent controls. Similarly, both ground- and canopy-nesters were more abundant at fledgling treatment plots relative to silent controls. Ovenbirds appeared to assess territory quality by integrating multiple social cues for territory establishment, but Veeries did not. My study demonstrates that post-breeding PI reaches heterospecifics by influencing territory establishment among both ground- and canopy-nesters. This study is the first to test if songbirds integrate social information from multiple sources throughout the breeding season for territory selection.