Fitness costs and benefits of cowbird egg ejection by gray catbirds
Bibliographic record
Abstract
Gray catbirds (Dumetella carolinensis) eject over 95% of brown-headed cowbird (Molothrus ater) eggs placed into their nests. Ejection behavior could be maintained by selection from either: (1) cowbird parasitism, if the costs of accepting a cowbird egg outweigh the costs of ejecting it, or (2) conspecific parasitism, if such parasitism occurs naturally and results in ejection. This study tested the above hypotheses by measuring the cost of acceptance of cowbird parasitism (n= 38 experimentally introduced cowbird chicks) and of cowbird egg ejection (n = 94 experiments), as well as the frequency of natural conspecific parasitism among 229 catbird nests observed and the frequency of conspecific egg ejection (n = 27 experiments). The conspecific parasitism hypothesis was not supported because catbirds accepted all foreign conspecific eggs placed into their nests, and no natural conspecific brood parasitism was detected at any nests. The cowbird parasitism hypothesis was strongly supported because the cost of accepting a cowbird chick (0.79 catbird fledglings) is much greater than the cost of ejecting a cowbird egg (0.0022 catbird fledglings per ejection).
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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 | 0.000 | 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) | 0.001 | 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".