Individual variation in diurnal body temperature and foraging activity in overwintering black-capped chickadees (Poecile atricapillus)
Bibliographic record
Abstract
Small birds in winter can mitigate energetic shortfalls via increases in foraging and/or via controlled reductions in metabolic rate and body temperature (torpor). The ability to both increase foraging and use torpor during the day could have profound implications for an individual's daily energy budget and overwinter survival. Trade-offs between foraging efficiency and daytime torpor use may exist but have not been explicitly investigated. Here, we investigated the presence of within- and among-individual correlations between daytime body temperature (T b, a proxy for torpor use) and foraging in overwintering black-capped chickadees ( Poecile atricapillus ). Using temperature-sensing passive integrated transponder tags, we measured daytime T b and foraging in 20 free-living chickadees over 49 days in a single winter (January–February). Chickadees generally exhibited T b around normothermic levels with an average T b during visits to the feeder of 41.7 °C, though T b ranged between 25.0 and 44.9 °C. Chickadees exhibited moderately lower daytime T b , shorter time intervals between successive feeder visits (IVI), and increased feeder visits as ambient temperature decreased. However, within individuals there was only evidence of a weak positive correlation between visit T b and IVI, and no correlation between daily feeder visits and daily mean visit T b. We found that visit T b , daily mean visit T b , and daily feeder visits were repeatable, while IVI was not. Sex did not explain a significant amount of variation in total daily feeder visits or daytime T b , nor was there evidence of among-individual correlations between daily mean visit T b and daily feeder visits. Our results suggests that chickadees may independently regulate foraging and diurnal T b . Overall, our study provides insights into how small birds in winter can use multiple strategies to overcome energetic challenges. Future studies investigating diurnal torpor and its integration with other strategies are needed to further elucidate how small birds survive harsh winter conditions. • We measured diurnal body temperature (T b ) and foraging rate in wintering chickadees. • Chickadees sometimes had below normothermic T b while actively foraging. • T b decreased and foraging rate increased at low ambient temperatures. • There was limited evidence of within-individual correlations between these traits. • Diurnal T b and daily feeder visits were both repeatable, but not correlated.
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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 | 0.001 | 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) | 0.000 | 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 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".