Plasma Metabolites and Mass Changes of Migratory Landbirds Indicate Adequate Stopover Refueling in a Heavily Urbanized Landscape
Bibliographic record
Abstract
Large concentrations of migrating landbirds in cities have been well documented, but the refueling conditions urban stopover sites provide are almost entirely unknown. We compared plasma triglyceride (indicator of mass gain) and B-OH-butyrate (indicator of mass loss) concentrations in landbirds in three New York City forests to those of conspecifics in two less disturbed, non-urban forests outside the city to evaluate the quality of urban stopover habitats. We quantified diurnal mass gains with regressions of body mass and capture time and measured arthropod biomass in leaf litter to assess food abundance for ground-foraging insectivores. Metabolite concentrations in Ovenbirds (Seiurus aurocapilla) at urban and non-urban sites did not differ during spring or autumn. In autumn, triglyceride levels of Swainson's Thrushes (Catharus ustulatus) indicated significantly higher refueling rates at the urban sites. In the Yellow-rumped Warbler (Dendroica coronata), butyrate was lowest out-side the city, suggesting better refueling conditions there, but differences in triglyceride did not suggest a consistent difference between the habitats in refueling rates. Autumn triglyceride and butyrate levels of three additional species did not indicate different rates of refueling within and outside the city. In the city, significant mass-gain rates ranged from 1.0 to 2.5% of total body mass hr-1. At no point during either season was there a consistent difference between habitat types in arthropod biomass. Our results suggest that although the availability of stopover habitats may be low in cities, migrating birds using these sites may refuel at rates comparable to those stopping in less disturbed areas.
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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 | 0.000 | 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".