Wintering closer to breeding grounds comes at a cost in an Arctic-specialized songbird, <i>Plectrophenax nivalis</i> (Snow Bunting)
Bibliographic record
Abstract
ABSTRACT Wintering at high latitudes may offer Arctic-breeding migratory birds advantages such as shorter migration distances and earlier arrival at breeding sites, potentially improving reproductive success. However, wintering at northern sites may also come at a cost as birds can experience colder and harsher conditions than individuals wintering farther south, consequently requiring physiological adjustments for life in the cold. We compared the physiological costs of wintering at different latitudes in Plectrophenax nivalis (Snow Bunting) from an Eastern Canadian population during the peak of winter. We hypothesized that individuals wintering at higher (i.e., colder) latitudes would be structurally larger, have better thermal insulation, maintain thicker pectoralis muscles and more lean tissues, carry larger lipid reserves, and experience greater physiological maintenance costs compared to individuals wintering at lower (i.e., warmer) latitudes. Contrary to our expectation, structural size did not differ between wintering sites. However, northern birds were 8% heavier and carried 32% more lipid reserves, suggesting increased energy storage for cold endurance. These birds also had 4% more lean mass and maintained slightly thicker pectoralis muscles, consistent with greater shivering thermogenesis capacity. Notably, basal metabolic rate (BMR), corrected for lean mass, was 6% higher in northern birds, indicating elevated physiological maintenance costs in colder environments. These findings therefore show that P. nivalis must pay a significant and measurable cost when wintering in colder environments to benefit from the potential fitness advantage of a shorter migration distance to their Arctic breeding grounds. Our study illustrates the physiological trade-off migratory birds face when selecting wintering locations and underscores the importance of considering both ecological benefits and metabolic costs when studying avian life-history strategies under variable climatic conditions.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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 teacher head, 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".