Meeting Abstract
Though altricial young are typically isolated in nests or burrows during development, they may be influenced by their surrounding environment. For instance, acoustic signals between conspecifics, including parents, may be received by developing young, and nestlings may respond behaviorally to calls from predators, conspecifics, and parents; however, little is known about physiological responses to such signals. We hypothesized that Florida scrub-jay (Aphelocoma coerulescens) nestlings would alter steroid levels in response to conspecific call playback and parental defense. We conducted conspecific, heterospecific, or no call playback at nests, recorded parental and nestling behavioral responses, and measured corticosterone (CORT) and testosterone (T) in nestlings. Adults responded aggressively to conspecific call playback, but nestling behavior did not differ from controls (begs, begging time, and feedings, p > 0.3). Nestling T (p > 0.3) and CORT (p > 0.3) did not differ from controls immediately following playback, but following the stress of a 10 min restraint, nestlings exposed to conspecific call playback had higher stress-induced CORT levels than nestlings exposed to no playback (p = 0.001). These results suggest that, while not directly influencing baseline CORT in nestlings, conspecific vocal cues may nevertheless prime the HPA axis for a heightened response to subsequent stress. As developmental CORT exposure can affect growth rates and body size of nestlings, as well as have long-term effects on HPA axis responsiveness and behavioral phenotype, these results may have implications for high-density populations in which aggressive encounters are common or species for which vocal communication is prominent.
