Lack of Stable-Isotope Differences between Canada Goose Populations Nesting in the Subarctic and Temperate Zones
Bibliographic record
Abstract
Ratios of stable isotopes in feathers have great potential for identifying the connectivity of bird migrations and the origin of harvested individuals of game species. In particular, the relationship between the hydrogen ratio due to latitudinal variation in precipitation (δDp) and that in feathers (δDf) is often used to determine unknown individuals' latitude of origin. We assessed this relationship between Canada Geese nesting in the temperate zone (Branta canadensis maxima) and the subarctic (B. c. interior). For this game species, the origin of harvested birds is important for developing management that maintains a desirable level of harvest while ensuring continued viability of all subspecies and breeding populations. We collected freshly grown primaries from three populations of interior and five of maxima and analyzed them for δD, δ13C, and δ15N. Multivariate analysis suggested no overall differences in isotopic composition between subspecies. A univariate assessment indicated a significant difference in δ15Nf, despite substantial overlap between subspecies, and no difference in δDf or δ13Cf. Of particular interest is the lack of difference in δDf, despite the large latitudinal differences in δDp and between the subspecies' breeding ranges. Values of δDf averaged -131.85‰ ± 1.36 for interior, -131.63‰ ± 0.71 for maxima, and we found no overall relationship between δDf and δDp. Overall, our results suggest that δD, δ13C, and δ15N alone have limited ability to discriminate between subspecies interior and maxima and hence have limited applicability for estimating the origin of harvested birds and/or identifying molt migrants of maxima.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".