Collaborative Research: Social modulation of migratory timing and endocrine mechanisms of migration in two flexible migrants

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Animal migration is a centrally important life cycle stage for thousands of species, it is critical to the dynamics of many ecosystems, has impacts on human health, and is a process that is particularly prone to disturbance. Thus, research on the control of migration is critical from both basic and applied perspectives. Understanding how animals decide when to move is of particular importance given that this can dictate whether or not they arrive at their destination at an appropriate time for reproduction or overwintering. Many animals move in groups and social interactions and social cues are expected to be important in the decisions that animals make in preparation for and during migration. Yet, there is little known about the role of social cues in determining when animals begin or end migration or about the physiological mechanisms by which social signals might act to influence migratory timing. This collaborative project will address these two knowledge gaps using two species of migratory songbirds that have flexible migratory schedules and that are highly sensitive to social information. Results of this work will advance our understanding of how social cues influence both migratory timing and the hormonal regulation of migration. This project will also provide training and mentoring for undergraduate and graduate students. Outreach activities linked to the project will engage elementary school students and the general public in migratory biology. Training and outreach activities at the university level and in elementary schools will target individuals from groups that are traditionally underrepresented in STEM fields.The first goal of this collaborative project is to evaluate the influence of social cues (specifically, the migratory state of conspecifics) on the timing of migration. Experiments will be carried out to test the hypotheses that birds use cues from conspecifics to fine-tune timing of initiation and termination of migration. Social cues have not been well studied in the context of migratory timing and the project's inclusion of the termination phase of migration will be important in advancing the understanding of this particularly understudied phase of migration. The second goal of the project is to advance understanding of the endocrine and neuroendocrine regulation of migratory transitions, with the further objective of investigating how social cues influence endocrine and neuroendocrine parameters to potentially alter migratory timing. Thus, investigators will quantify changes in circulating steroid hormones and the availability of their receptors in the brain and peripheral tissues across transitions into and out of a migratory state. This type of whole-body approach to understanding endocrine mechanisms in the context of migration is unique. The investigators will also experimentally manipulate social cues to evaluate endocrine and neuroendocrine mechanisms by which these cues might influence migratory timing. The results of this project will thus greatly broaden understanding of the roles of social cues and plasticity of endocrine mechanisms in life history transitions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.