Carotenoid concentration and coloration of American Kestrels (<i>Falco sparverius</i>) disrupted by experimental exposure to PCBs
Bibliographic record
Abstract
Summary Bright coloration in birds is typically a sexually selected trait. Expression of such traits is sensitive to environmental factors, so they can function as bioindicators of environmental contamination. Of particular value may be carotenoid‐based coloration because it is commonly used as a social signal and these pigments have important health functions. American Kestrels (Falco sparverius) in captivity were exposed to dietary PCBs in March. Colour and plasma carotenoids of exposed and control birds were evaluated at pairing and courtship in April, and in winter in December. Juveniles produced by these birds (exposed to PCBs only in ovo) were examined at fledging and in winter. The brightly coloured ceres and lores were evaluated by comparison to colour charts and quantified using digital photographs, and plasma carotenoid concentrations were quantified by spectrophotometry. During breeding, PCB‐exposed kestrels differed from controls for both colour and carotenoids, although the nature of effects was sex‐specific. Carotenoids of juveniles were not related to treatment at fledging. In winter, PCB‐exposure resulted in patterns of colour/carotenoid variation opposite to controls; exposed adult males were duller, and juveniles of both sexes were brighter, than controls. PCB juveniles had higher plasma levels of carotenoids. Sexual dimorphism was apparent in colour and carotenoids of control adults, but not for PCB‐exposed birds. Our results are consistent with endocrine disruption. Modulation of both colour and carotenoids may have serious consequences to social behaviour and health.
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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 | 0.001 |
| 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".