Symposium Paper: Pre-breeding Diet, Condition and Timing of Breeding in a Threatened Seabird, the Marbled Murrelet Brachyramphus Marmoratus
Bibliographic record
Abstract
Pre-breeding diet, condition and timing of breeding in a threatened seabird, the Marbled Murrelet Brachyramphus marmoratus.Marine Ornithology 37: 33-40.Marbled Murrelets Brachyramphus marmoratus are small, threatened seabirds that nest in old-growth coniferous forests along the west coast of North America and spend most of their lives in nearshore waters.Recent evidence suggests that long-term declines in pre-breeding trophic feeding level may be associated with reduced reproductive success.To test the hypothesis that pre-breeding trophic feeding level positively influences breeding success, we investigated relationships between timing of breeding, female body condition and pre-breeding trophic feeding level.We predicted that females feeding on higher trophic level prey before breeding would be in better condition and would initiate egg production earlier than would females feeding on lower trophic level prey.Egg-producing females were identified based on elevated yolk precursor (vitellogenin) levels, and diet composition was inferred using stable carbon (δ 13 C) and nitrogen (δ 15 N) analysis of murrelet and prey tissues during the pre-breeding seasons of 1999, 2000, 2006 and 2007 in Desolation Sound, British Columbia.Contrary to our predictions, females feeding on a higher proportion of low trophic level prey in 2007 were in better condition and were more likely to produce an egg early in the breeding season.However, differences in pre-breeding diet between egg-producing and non-egg-producing females were not consistent among years.Although our results suggest that low trophic level prey in the pre-breeding diet promoted egg production and breeding success in 2007, this was likely not the case in other years studied.To reconcile results presented here and previous work on diet composition and breeding success in the Marbled Murrelet, we propose an alternative hypothesis of diet quality incorporating optimal foraging theory, whereby the net energy gain from feeding on a prey type is a function of its relative availability.
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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 | 0.000 | 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) | 0.004 | 0.001 |
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".