Stable-Carbon and Hydrogen Isotope Ratios Reveal Breeding Origins of Red-Winged Blackbirds
Bibliographic record
Abstract
We investigated the potential of using stable-carbon (δ13C) and hydrogen (δD) isotope ratios in feathers of Red-winged Blackbirds (Agelaius phoeniceus) to delineate geographic origins where feathers were grown. We used outer primary feathers from territorial male blackbirds along a broad latitudinal transect from Louisiana, USA to Saskatchewan, Canada. Feather δD values showed an expected depletion with latitude, and were correlated strongly (r2 = 0.83) with the mean growing season δD for precipitation at collection sites. Feather δ13C values revealed that blackbirds fed on both C3 and C4 based foodwebs. Inputs of C4-based carbon likely related to consumption of agricultural crops such as corn and sorghum. Overall, our dual isotope approach showed great potential as a means of delineating breeding origins of blackbirds throughout the continental Midwest, and supports previous findings that δD measurements of feathers are strongly correlated with precipitation and latitude throughout the central region of the continent.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.009 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".