Seasonal Decline in Nestling Growth: Support for the Parental-Quality Hypothesis in Cassin's Auklets
Bibliographic record
Abstract
Growth rates of nestlings often decline over the breeding season (e.g. Birkhead and Nettleship 1982, Gaston et al. 1983, Morbey and Ydenberg 1997, Lepage et al. 1999). Although several mechanistic hypotheses have the potential to explain this phenomenon (see Nilsson 1999), we investigated the two that are considered most often. Under the date hypothesis, nestling growth depends indirectly on current environmental conditions through direct effects on parental provisioning. A seasonal decline in nestling growth is expected if feeding conditions deteriorate over the season. Under the parental-quality hypothesis, young or inexperienced parents, or those with lower provisioning ability, initiate breeding later, leading to a seasonal decline in nestling growth. We determined which hypothesis could best explain the observed seasonal decline in nestling growth rates of Cassin's Auklets (Ptychoramphus aleuticus) by comparing growth of nestlings whose hatching dates were normal versus experimentally delayed. Breeding phenology and nestling growth of Cassin's Auklets were monitored in 1994 on Triangle Island (50°52′N, 129°05′W; Morbey and Ydenberg 1997). Cassin's Auklets lay one egg and incubate it for approximately 38 days, with parents switching incubation duties approximately every 24 h (Astheimer 1991). Prior to egg laying, we excavated 82 burrows to create access holes and began daily monitoring. If twigs that we placed in burrow entrances were knocked down the following day, we inferred that the burrow had been visited the previous night. Active burrows were checked every third day for eggs. Upon discovery of a newly laid egg, we alternately assigned the burrow to one of two experimental groups. In the delayed group (n = 27), the egg was replaced with a hard-boiled chicken egg for five days. In the interim, the auklet egg was left in a carton buried in the sand to keep it safe and cool. Enforcing egg neglect at the beginning of the incubation period was done to minimize any negative effects of interrupting embryonic growth. In the control group (n = 25), eggs were handled as in the delayed group but were not removed for more than a few seconds. Hatching dates of these experimental burrows were expected to span the natural range.
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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 | 0.001 | 0.001 |
| 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".