Stable Isotopes (δD) Reveal East–West Differences in Scheduling of Molt and Migration in Northern Rough-Winged Swallows (<i>Stelgidopteryx serripennis</i>)
Bibliographic record
Abstract
We used stable-isotope (δD) measurements of primary feathers to demonstrate that Northern Rough-winged Swallows (Stelgidopteryx serripennis) that breed in western North America migrate to the monsoon region of northwest Mexico for their annual postbreeding molt. Both adults and juveniles replace all their primaries in late summer. As expected, in samples of adults and fledglings collected at a northern breeding locality in eastern Washington, primary δD values of adults were of southern origin, whereas those of fledglings, whose feathers were grown in the nest, were consistent with their northern origin. Similarly, some young birds collected as they were replacing primaries in northwest Mexico had a southern signature in newly replaced primaries but a northern signature in their yet unreplaced juvenile primaries, which indicates that they were molt migrants from the north. Feather OD values increased from P1 to P9 in breeding adults collected in upstate New York. In the eastern United States, both adults and juveniles replace their primaries as they migrate southward in the fall. These isotopic results are consistent with the observation that Northern Rough-winged Swallows are halfway through their primary molt when they reach the Gulf Coast, where they pause in coastal marshes to finish the primary molt before crossing the Gulf of Mexico. The striking difference in molt and migration schedules between eastern and western populations of Northern Rough-winged Swallows suggests further investigations of their species status be conducted in the region where these populations make contact.
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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) | 0.000 | 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".