Food and feeding ecology of the sympatric thin-billed <i>Pachyptila belcheri</i> and Antarctic <i>P. desolata</i> prions at Iles Kerguelen, Southern Indian Ocean
Bibliographic record
Abstract
The food and feeding ecology of the 2 closely related species of prions <i>Pachyptila belcheri</i> and <i>P. desolata</i> was investigated over 3 consecutive chick-rearing periods at Iles Kerguelen, the only place where they nest sympatrically in large numbers. In all years, the 2 prion species fed on crustaceans, with a small proportion of mesopelagic fish and squid. The hyperiid amphipod <i>Themisto gaudichaudii</i> was consistently the dominant prey item, accounting for 76 and 70% by number, and 57 and 57% by reconstituted mass of the diet of <i>P. belcheri</i> and <i>P. desolata</i>, respectively. Prions, however, were segregated by feeding on different euphausiids, <i>P. belcheri</i> on <i>Thysanoessa</i> sp. (18% by number and 16% by mass) and <i>P. desolata</i> on <i>Euphausia vallentini</i> (9% by number and 15% by mass). <i>P. desolata</i> also caught more small prey such as copepods (9 vs <1% by number) and cypris larvae of <i>Lepas australis</i> (8 vs 3% by number) than <i>P. belcheri</i>, which can be related to the beak filtering apparatus present only in the former species. Biogeography of the prey and their state of digestion indicate that prions foraged in a wide variety of marine habitats, including the kelp belt, kelp rafts, and coastal, neritic and oceanic waters. Noticeable is the occurrence of <i>E. superba</i> in a significant number of food samples (15 and 10% for <i>P. belcheri</i> and <i>P. desolata</i>, respectively), suggesting feeding in distant foraging grounds in southern Antarctic waters, >1000 km from the breeding colonies, during the chick-rearing period. The stable-carbon and -nitrogen isotopic compositions of chick feathers were identical in both species, indicating no important trophic segregation during the breeding period, when adult birds are central-place foragers. The ratios were, however, different in adult feathers, suggesting moulting in Antarctic waters for <i>P. belcheri</i> and in subtropical waters for <i>P. desolata</i>, i.e. in distinct foraging areas when birds are not constrained to return to the colonies.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.003 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.005 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.003 | 0.015 |
| Research integrity | 0.002 | 0.002 |
| 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; both teacher heads agree on what is shown here.
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".