An evaluation of migration fidelity of Ruby-throated Hummingbirds inferred from stable isotope methods
Bibliographic record
Abstract
Knowledge of spatial connectivity between breeding and non-breeding locations of migratory birds and their breeding site fidelity are important for avian conservation. Ruby-throated Hummingbirds (RTHU, Archilochus colubris) breed in eastern Canada west to the Rocky Mountains and in the USA east of the Mississippi River and spend the non-breeding period in Mexico, Central America, and southern Florida, USA. We measured the hydrogen and oxygen stable isotopic compositions of adult RTHU tailfeathers (fourth rectrix) from three breeding locations in North America to estimate migratory connectivity between breeding and non-breeding grounds where feathers are grown. Feather δ2H values showed no statistical difference among the three sampling locations as well as disparate geographic assignments from one location on the non-breeding grounds in Costa Rica. Therefore, only weak evidence of migratory connectivity between breeding and non-breeding grounds could be ascertained for our sample of this species. The lack of migratory connectivity detected for Ruby-throated Hummingbirds using stable isotopes is consistent with origins from broad regions on the non-breeding grounds. However, it may also imply that precipitation δ2H values on the non-breeding grounds do not vary enough to detect a difference among our study populations. Sampling of additional populations in the eastern and southern portion of the species’ breeding range and the non-breeding grounds may reveal differences in migratory connectivity among populations and requires further investigation. The δ18O values of feathers correlated poorly to their δ2H values, an effect that may reflect the balance between metabolically driven processes and environmental water on the δ18O values of hummingbird tissues. This study provides the foundations for further investigations into migratory connectivity of RTHU using δ2Hf values and suggests potential avenues of study for use of δ18O values of tissues in metabolic research.
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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 | 0.002 |
| 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".