Individual timing consistency across purple martin (Progne subis) migrations
Bibliographic record
Abstract
Migration timing in long-distance migratory birds plays an essential role in individual survival and fitness. Migration schedules determine when individual birds depart and arrive seasonally between their overwintering and breeding sites. Bird migration timing may be largely driven by internal routines with some plasticity to environmental conditions, but individual timing across migrations has been little explored. To investigate the consistency of individual timing across migrations, I examined the individual order of migration timing in purple martins (Progne subis), a neotropical migratory songbird that travels between breeding sites throughout eastern North America and winter sites in Brazil. Migration timing data were collected for 295 different individual purple martins spanning over nine years by using light-level geolocators deployed during the breeding season at sites across the range and collected at the same sites the following year. I used a linear mixed-effect model (LMM) to examine the influence of the rank order of departure dates in one season on the rank order of four subsequent migration events while controlling for the effects of breeding latitude, sex, and age. Overall, I found that the individual rank order of migration timing in purple martins was conserved across migrations. Rank order timing was consistent between fall departure date from the breeding site and spring arrival dates in the following year (0.28 0.03, 95% CI 0.21-0.34), as well as the finer scale across fall migration departure and arrival dates (0.33 0.05, 95% CI 0.23-0.42), over the wintering period (0.39 0.04, 95% CI 0.30-0.48), and across spring migration (0.03 0.001, 95% CI 0.026-0.033). These results demonstrate that purple martin exhibit consistency in individual migration timing throughout the annual cycle. Migration distance also played a significant role, as the consistency of rank order timing lessened with distance traveled. Understanding how individual birds time migrations and if individuals are consistent between events can provide insight into how shifts in the environment with climate change could lead to a mismatch if migratory birds are unable to adapt. Future studies should examine if purple martins are able to adjust their migration timing and how long these changes persist in response to environmental alterations.
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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 | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".