Diet and trophic position of Leachs storm-petrel Oceanodroma leucorhoa during breeding and moult, inferred from stable isotope analysis of feathers
Bibliographic record
Abstract
We combined conventional dietary sampling (2002) with stable isotope analysis of nitrogen ( 15 N) and carbon ( 13 C) in feathers of Leach's storm-petrels Oceanodroma leucorhoa (2001 and 2002) to investigate temporal, sex-and age-related variation in diet and trophic position, at Baccalieu Island, Newfoundland, Canada. Nestlings are fed mainly fish and crustaceans (ca. 90 and 9% by mass, respectively) toward the end of chick-rearing. The bulk of the fish were vertically migrating myctophids, associated with the offshore environment. Crustaceans were mainly parasitic hyperiid amphipods Hyperia galba, commonly found nearshore in association with scyphozoan jellyfish hosts. 15 N values in summer-grown feathers were similar between years, but differed between age-classes in 2001 when chicks occupied slightly higher trophic level (3.2 vs. 3.1). 13 C values in summer-grown feathers were lower for chicks than adults. Predictions from a 3-source dual-isotope linear mixing model indicated that adults consumed 47% glacier lanternfish Benthosema glaciale, 5% capelin Mallotus villosis and 49% H. galba in 2001, while in 2002 respective values were 87, 6 and 7%. Model output for chicks was not biologically meaningful, possibly due to the lipid-rich (and 13 C depleted) stomach oil fed to chicks by adults. For adults, no sex differences were found in values of either isotope during summer. 15 N values were significantly higher in feathers grown during summer than during mid-moult, suggesting increased consumption of crustaceans in winter. 13 C values in adult primaries were relatively enriched, consistent with movement of post-breeding birds toward tropical waters. Combining conventional and chemical analyses has provided some of the first insights into the year-round ecology of the smallest and most abundant seabird breeding in eastern North America.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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 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".