Yolk and Feather Carotenoids in Relation to Female Condition and Reproduction in the Yellow-headed Blackbird (<i>Xanthocephalus Xanthocephalus</i>)
Bibliographic record
Abstract
Carotenoids can be important antioxidants and immunostimulants for developing embryos and adult birds, and they are often incorporated into colorful sexual displays as signals of individual quality. The allocation of carotenoids to egg yolks and feathers can be affected by a female's physical condition, which can in turn affect offspring growth and survival. We examined relationships between yolk and feather concentrations of carotenoids and various indices of female quality (i.e., body condition, heterophil-to-lymphocyte ratio, hematocrit, date of nest initiation, egg mass, reproductive success) in the Yellow-headed Blackbird (Xanthocephalus xanthocephalus), a brightly colored passerine. Measures of physical condition of female Yellow-headed Blackbirds were correlated with the allocation of carotenoids to both eggs and feathers. Specifically, less stressed (i.e., lower heterophil-to-lymphocyte ratio) females had higher concentrations of β-carotene in their eggs than females that were more stressed. In addition, females with higher hematocrit values (i.e., more red blood cells) had higher concentrations of feather carotenoids. Timing of breeding was also related to variation in yolk carotenoid concentrations; later-breeding females produced eggs with lower concentrations of β-carotene but higher concentrations of lutein, which could be due to renesting or seasonal differences in carotenoid availability and use. Concentrations of yolk and feather carotenoids were not correlated, which suggests that individual carotenoids may have different functions in eggs and plumage. Carotenoid concentrations and female condition variables were not significantly related to the reproductive traits measured, but small sample sizes of females that fledged young may have limited our ability to detect effects. Our results highlight the need for further studies on the condition-dependent allocation and use of carotenoid pigments for reproduction and sexual signals in brightly colored female birds.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 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) | 0.000 | 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 teacher head, 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".