title: Chronologically sampled flight feathers permits recognition of individual molt-migrants due to varying protein sources.
abstract: This is a proof of concept paper based on chronological samples of growing feathers from geese thought to be molt-migrants. When molt-migrant birds initiate molt shortly after migrating to a new isoscape, isotope values measured along the length of their feathers should change continuously. To assess long-term changes and daily cycling in δ (15)N and δ (13)C values, we serially sampled a growing primary from three presumed molt-migrant geese. Two showed changing δ (15)N signatures along the length of their growing primary, indicating they were molt-migrants, while the third, presumably a resident, showed no change. We then resampled these feathers at closer intervals for evidence of the predicted diel cycle in the use of exogenous and endogenous protein for feather growth, generated by the diel feeding cycle of these geese. As predicted, a periodicity of ca. 24 h in δ (15)N values was found along the primary of the two equilibrating geese, but not in the other goose that was probably a resident. Our results demonstrate that chronological sampling along the length of individual primaries holds great potential for identifying individuals that are molt-migrants.
authors: Department of Biology and Burke Museum, University of Washington , Seattle, WA , USA.
authors: Sievert
authors: S
authors: Rohwer
authors: Department of Bioscience, University of Aarhus , Kalø, Grenåvej, Rønde , Denmark.
authors: Anthony D
authors: AD
authors: Fox
authors: Department of Biology, University of Washington , Seattle, WA , USA.
authors: Thomas
authors: T
authors: Daniel
authors: Oklahoma Biological Survey and Department of Biology, University of Oklahoma , Norman, OK , USA.
authors: Jeffrey F
authors: JF
authors: Kelly
keywords: 15-nitrogen; Diel cycling; Feather chronology; Isotopes; Molt-migration
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