Investigating the role of call similarity in a tree swallow (Tachycineta bicolor) parent-offspring recognitionmechanism

Abstract

Parent-offspring recognition is a mechanism that allows parents and offspring to recognize each other by specific cues. The mechanism is predicted to be well developed in species that are at a high risk for misdirecting care awayfrom related individuals (e.g. colonial species). Tree swallows, a semi-colonial species, exhibit characteristics of parent-offspring recognition in the vocal interactions between older nestlings and parents. The design and ontogeny of the mechanism in tree swallows, however, is poorly understood. Call similarity between parents and nestlings from the same nest is one such design that facilitates recognition. We tested for similarity between the begging calls and contact calls of nestlings and parents from the same nest, and we used a cross-fostering experiment to determine if the similarity was derived from a learning mechanism or by genetic inheritance. We found very little significant evidence of similarity between nestling and parent calls from the same nest, either under the learning mechanism or the inheritance mechanism. Our results suggest that the parent-offspring recognition mechanism in tree swallows is not based on call similarities between nestlings and parents. However, the results may also suggest that call individuality is more important to the mechanism than call similarity. Further research is required to confirm the assumptions of our study.