Linking hydrogen (Œ¥2H) isotopes in feathers and precipitation: sources of variance and consequences for assignment to isoscapes
Authors: Leonard I Wassenaar
Keith Larson
Steven L Van Wilgenburg
Keith A Hobson
Journal: PLoS ONE (2012)
Discipline: Multidisciplinary
Keywords: migrant organisms; stable isotopes; feathers; animal origin; hydrological flow
Affiliations: Environment Canada, Saskatoon, Saskatchewan, Canada. 

Abstract:  Background: Tracking small migrant organisms worldwide has been hampered by technological and recovery limitations and sampling bias inherent in exogenous markers. Naturally occurring stable isotopes of H (Œ¥(2)H) in feathers provide an alternative intrinsic marker of animal origin due to the predictable spatial linkage to underlying hydrologically driven flow of H isotopes into foodwebs. This approach can assess the likelihood that a migrant animal originated from a given location(s) within a continent but requires a robust algorithm linking H isotopes in tissues of interest to an appropriate hydrological isotopic spatio-temporal pattern, such as weighted-annual rainfall. However, a number of factors contribute to or alter expected isotopic patterns in animals. We present results of an extensive investigation into taxonomic and environmental factors influencing feather Œ¥(2)H patterns across North America. Principal findings: Stable isotope data were measured from 544 feathers from 40 species and 140 known locations. For Œ¥(2)H, the most parsimonious model explaining 83% of the isotopic variance was found with amount-weighted growing-season precipitation Œ¥(2)H, foraging substrate and migratory strategy. Conclusions/significance: This extensive H isotopic analysis of known-origin feathers of songbirds in North America and elsewhere reconfirmed the strong coupling between tissue Œ¥(2)H and global hydrologic Œ¥(2)H patterns, and accounting for variance associated with foraging substrate and migratory strategy, can be used in conservation and research for the purpose of assigning birds and other species to their approximate origin. 

Retracted: No

PubPeer comments:
 - I think the regression lines might be mislabeled. For example, in Figure 2B, unless I am mistaken, the lower line should have the lower intercept and, with the current legend, maybe it should be solid instead of dashed? - My understanding of how the authors divided the data based on migratory behaviour, a given individual should only be represented once in panels 2B-D. From looking at the figures, however, it looks as if there are several shared points between the panels (e.g. the individual with the highest deuterium value, ~0ppt, is in both the neotropical migrant panel 2B and the resident panel 2D). This is similar for the two clusters of points around -105ppt in 2B and 2C. It is unclear if these individuals were just misplaced, or the models incorrectly included them as well.  , 
 #1 Apologies for a late response but I have a new email address (Western University) and I am trying to track down the co-author who did the original data analysis. We will post an erratum here and hopefully with the original journal. Thank you for the forensic analysis and we look forward to providing a list of checked calibration algorithms and hopefully new figures. , 
  New figure now constructed. We will submit an erratum to PLoSONE ,