Corticosterone release in very young siblicidal seabird chicks ( <i>Rissa tridactyla</i> ) is sensitive to environmental variability and responds rapidly and robustly to external challenges
Bibliographic record
Abstract
In birds, patterns of development of the adrenocortical response to stressors vary among individuals, types of stressors, and species. Since there are benefits and costs of exposure to elevated glucocorticoids, this variation is presumably a product of selection such that animals modulate glucocorticoid secretion in contexts where doing so increases their fitness. In this study, we evaluated hypothalamic-pituitary-adrenal (HPA) activity in first-hatched free-living seabird nestlings (black-legged kittiwakes, Rissa tridactlya ) at a critical early age when food availability may drive the establishment of important parent-offspring and intra-brood dynamics. We experimentally supplemented parents with food (fed) and measured chick baseline corticosterone secretion at 5 days post-hatch (of the ~45 day nestling period) and capacity to rapidly increase corticosterone in response to an acute challenge (handling and a 15 min restraint in a bag). We also used topical administration of corticosterone to evaluate the ability of chicks to downregulate physiologically relevant corticosterone levels on a short (minutes) time scale. We found that 5 day old chicks are capable of releasing corticosterone in proportion to the magnitude of the challenge, showing differences in baseline between parental feeding treatments (supplementally-fed vs control), moderate increases in response to handling, and a larger response to restraint (comparable to restraint-induced levels found in adults) that also differed between chicks from fed and control nests. The topical application of exogenous corticosterone resulted in an increase of circulating levels similar to the restraint-induced levels. The corticosterone application also induced the downregulation of HPA responsiveness to the acute challenge of handling. Parental supplemental feeding did not affect absorbance/clearance or negative feedback. Thus, while endogenous secretion of corticosterone in 5 day old chicks is sensitive to environmental context, other aspects of the HPA function, such as rapid negative feedback and/or the ability to clear acute elevations in corticosterone, are not. We conclude that 5 day old kittiwake chicks are capable of robust adrenocortical responses to novel challenges, and are sensitive to parental food availability, which may be transduced behaviorally, nutritionally, or via maternal effects. Questions remain about the function of such rapid, large acute stress-induced increases in corticosterone in very young chicks.
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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 | 0.001 |
| 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".