LOW FREQUENCY OF “DOUBLE MOLT” OF REMIGES IN RUDDY DUCKS REVEALED BY STABLE ISOTOPES: IMPLICATIONS FOR TRACKING MIGRATORY WATERFOWL
Bibliographic record
Abstract
Ratios of the stable carbon (δ13C) and hydrogen (δD) isotopes in newly grown remiges of Ruddy Ducks (Oxyura jamaicensis) are influenced by the isotopic character of food types and ambient water. Systematic isotopic foodweb and water differences between coastal wintering grounds and prairie breeding grounds of Ruddy Ducks provide the basis for using isotopic analyses of feathers to trace the location and timing of molt. Anecdotal evidence, based largely on captive birds, suggests that Ruddy Ducks replace their remiges twice each year (once each on the breeding and wintering grounds), but a recent literature analysis indicates that this phenomenon is rare. Thus, we investigated the extent to which a biannual molt of the remiges occurs in the wild and at the population level. We analyzed the stable isotopes of carbon (n = 57 birds) and hydrogen (n = 50 birds) in flight feathers to estimate the prevalence of the so-called “double molt” of remiges in free-living Ruddy Ducks. Our data showed that natural populations of Ruddy Ducks express an overwhelming unimodal distribution of isotope ratios in their remiges, suggesting that they undergo a single molt at or near the breeding grounds. Only 3 to 6 of 50 birds from Manitoba showed isotopic evidence consistent with growing remiges on the wintering grounds. Feathers from Ruddy Ducks harvested during the fall in the Mississippi Flyway had isotopic profiles consistent with growth on northern freshwater breeding sites. Thus, our results confirm that the replacement of remiges twice each year by Ruddy Ducks is rare, and they suggest that this dual stable-isotope technique can be used to infer general molting origins of North American waterfowl.
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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 | 0.001 | 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) | 0.002 | 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".