Nestling condition of a grassland bird is not associated with food availability in restored grasslands
Bibliographic record
Abstract
Grassland bird populations have experienced steep declines in recent decades, necessitating better understanding of factors affecting their reproductive success. Grasslands are highly variable environments, and such variation affects the diversity and abundance of arthropods, which constitute the diet for most nestling grassland songbirds. Changes in arthropod abundance might affect parental food provisioning to nestlings and, consequently, nestling condition and survival. During the summers of 2017–2019, we examined the condition of Dickcissel (Spiza americana) nestlings from 288 nests in relation to biomass of arthropod prey across 36 restored grassland sites in Kansas that varied in vegetative management. Orthopteran (principal food for nestling Dickcissels) and total arthropod biomass were not related to cattle grazing or plant diversity in the initial seeding mix. Neither Dickcissel clutch size nor maximum brood size (including Brown-headed Cowbirds, Molothrus ater) were correlated with arthropod biomass measures in all years, which indicated that forage availability varied independently of clutch size. Neither age-corrected mass, mass/tarsus residuals, variation of tarsus length within broods, or plasma triglyceride concentration showed clear relationships with field-level variation in either arthropod biomass measure. This might be due to parental compensation for variable prey abundance. Brood size (including cowbirds) explained some variation in nestling condition with nestlings in larger broods generally exhibiting poorer condition (lower weight vs. structural size) than those in smaller broods. Thus, parents may be more limited in their capacity to feed all nestlings in large broods rather than limited by the availability of food within habitat patches. Consistent with previous hypotheses discounting food limitation to birds nesting in grasslands, our results suggest that Dickcissel nestling condition, known to affect post-fledging survival, might not be affected by spatial variation in food availability, at least in some years.
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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".