Genetic elucidation of host use by individual sympatric bronzed cowbirds (<i>Molothrus aeneus</i>) and brown-headed cowbirds (<i>M. ater</i>)
Bibliographic record
Abstract
Species of avian brood parasites that use one or several species of hosts are called host specialists and generalists, respectively. To determine host use of individual bronzed cowbirds, Molothrus aeneus (Wagler, 1829), and brown-headed cowbirds, Molothrus ater (Boddaert, 1783), we assigned maternity to eggs using microsatellite DNA markers. We measured patterns of host use by individual sympatric cowbirds. This allowed us to determine whether these species competed for host nests and the number of females laying at nests that were already parasitized by conspecifics. We monitored 1447 nests of 42 potential host species and found that each species of cowbird used primarily four host species, with minimal overlap in the species used, yet at least some individuals acted as generalists. Individual cowbirds tended to avoid laying again at nests each had already parasitized, and multiple parasitism was frequently due to same-day laying by more than one female (19% and 44% of 27 and 39 cases for brown-headed and bronzed cowbirds, respectively). Our results suggest that both cowbirds can differentially parasitize host species; however, host use does not appear to be refined, as many eggs were laid in already-parasitized nests when unparasitized nests of other suitable host species were available.
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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 | 0.001 | 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".