Stable isotopes document inter- and intra-specific variation in feeding ecology of nine large southern Procellariiformes
Bibliographic record
Abstract
Investigating the foraging ecology of seabirds is especially challenging given their wide-ranging movements and the practical difficulties of obtaining unbiased information on their feeding behavior.Despite the development of animal-borne tracking devices, several limitations preclude investigations at the scale of a whole community in a given season or year, and, until recently, during the non-breeding period.Here we analyzed δ 13 C and δ 15 N in feathers of chicks and adults to investigate inter-and intra-specific variation in the foraging habitat and trophic position of 9 large procellariiform seabirds from 6 southern breeding localities during the breeding and non-breeding periods.Isotopic ratios of each species were generally consistent among different breeding populations, despite the large geographical scale and potential variation in oceanography in surrounding waters.Both spatial and trophic segregation apparently allowed the coexistence of sympatric species in most breeding localities, except at South Georgia, where both δ 13 C and δ 15 N in chicks showed high overlap among species, probably resulting from the superabundance of alternative food resources during the summer.Low variance in stable isotope ratios among adults in several species indicated high overlap between individuals in feeding habits and trophic levels (i.e.isotopic specialist populations) during the non-breeding period.By contrast, large isotopic variances and the high within-and between-individual components of the trophic niche width suggested that grey-headed and light-mantled sooty albatrosses are generalists.Based on δ 13 C, the species that breed in the Southern Ocean can be categorized as residents or subtropical migrants, with the latter including oceanic and neritic subtropical migrants.Albatrosses meet the high energetic challenge of feather synthesis by foraging in different habitats, depending on the length of the non-breeding period.Annual breeders renew their plumage in productive neritic waters in ~4 mo, whereas biennially breeding species moult in less productive oceanic waters over much longer periods (~12 to 16 mo).
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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 | 0.000 |
| 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) | 0.001 | 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".