Use of Stable Isotope Methodology to Determine Natal Origins of Mallards at a Fine Scale Within the Upper Midwest
Bibliographic record
Abstract
Abstract: Waterfowl managers often attempt to protect local breeding stocks of mallards ( Anas platyrhynchos ) from hunting pressure, but presently they cannot identify natal origins of birds shot during fall hunting seasons with certainty, unless recovered birds are banded before fledging. Accordingly, we examined whether stable isotope methodology could accurately delineate natal origins of mallards at a fine scale within the upper Midwest (USA). We determined δ 13 C, δD, and δ 15 N values from feather samples of 102 flightless mallard ducklings collected in Minnesota, North Dakota, South Dakota, and Wisconsin, USA, from 7 July to 9 September 2002. We detected inverse relationships between latitude and δ 13 C( R 2 = 0.223) and δD( R 2 = 0.210). We also detected a weak positive relationship between easterly shifts in longitude and δ 13 C( R 2 = 0.067) and a weak negative relationship between easterly shifts in longitude and δ 15 N( R 2 = 0.076). The 13 C and deuterium values differed ( P < 0.02) among states: North Dakota was most depleted in 13 C, and South Dakota was least depleted in deuterium. Discriminant function analysis delineated natal origins of mallard ducklings in Minnesota, North Dakota, South Dakota, and Wisconsin with low‐to‐moderate accuracy (47%), whereas we predicted natal origins of ducklings among subregions (Prairie [ND, SD] vs. Great Lakes [MN, WI] states) with moderate accuracy (72%). We conclude that stable isotope methodology has a limited ability to determine natal origins of migratory birds along a longitudinal corridor at fine scales but that it improves across ecoregions. However, the ability of deuterium to determine natal origins of migratory birds may vary as hydrological conditions, within and among areas, change throughout time. Researchers should account for annual variation in deuterium found in surface waters when investigating natal origins of migratory birds that use food derived primarily from these waters.
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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 | 0.000 |
| 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 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".