Exploring overlap of feather molting and migration in tundra swans using δ²H analysis

• Main Authors: Wolf, N. (Nathan), Smeltz, S. (Scott), Welker, J. M. (Jeffrey M.), Rogers, M. C. (Matthew C.), Ely, C. (Craig)
• Format: Article in Journal/Newspaper
• Language: English
• Published: De Gruyter 2020
• Subjects: Deuterium; Precipitation; Satellite tracking; Stable isotopes; Variability; Tundra; Alaska
• Online Access: http://urn.fi/urn:nbn:fi-fe2021062940373

Abstract Determining the processes that shape the relative timing of energetically-costly events in the annual cycle of migrating birds is important to our understanding of avian phenology and ecology. We paired satellite tracking and hydrogen stable isotope analysis (δ²H) to examine the relative timing of two such events — migration and feather molting — in tundra swans from four breeding areas in Alaska, USA. Our results show a trend of increasing intra-individual variability in breast feather δ²H values with increasing migration distance, suggesting the overlap of breast feather molting and migration. However, when individual samples were pooled by breeding area, the δ²H values of breast and head feathers showed no trend with migration distance, presumably resulting from high levels of inter-individual variability in δ²H values within each breeding area. We explore potential reasons for this variability, propose potential mechanisms influencing feather δ²H values of tundra swans, and recommend further research into methods for exploring the temporal configuration of events in the annual cycle of migrating birds.