Testing the myth of humid versus dry cold: birds do not care
Bibliographic record
Abstract
ABSTRACT At high air temperatures (T a ) atmospheric water vapor can markedly influence an animal’s heat dissipation by reducing evaporative cooling capacities. At low T a however, the impact of increased water vapor on heat exchange has sparsely been investigated, despite human populations at northern latitudes insisting on feeling colder on days with higher humidity (i.e., humid-cold). Here, we aimed to investigate the humid-cold perception by determining whether Black-capped Chickadees ( Poecile atricapillus ) exhibited greater energy expenditure through increased heat loss under humid-cold conditions relative to dry-cold. We measured resting metabolic rates (RMR) of captive chickadees (n=10) during exposure to two T a treatments, below freezing (T a ≈ −7°C) and above freezing (T a ≈ 10°C), with either dry or saturated air. We found that T a substantially impacted RMR, with RMR ≈1.5-fold greater at −7°C compared with 10°C. Conversely, humidity did not have a statistically significant impact on RMR at either T a . Our data thus suggest that humidity does not significantly influence an individual’s heat exchange with the environment at cold T a . This presumably reflects the fact that cold air can hold minimal amounts of water vapor and any possible influence on heat loss is negligible. Instead, we suggest that a greater contributor to the humid-cold myth is the frequency of overcast days during which direct solar radiation is blocked. Summary statement Black-capped chickadees significantly increased their resting metabolic rates at air temperatures below freezing relative to air temperatures above freezing, whereas humidity level did not significantly affect resting metabolic rates.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".