Heat increment of feeding in double-crested cormorants (<i>Phalacrocorax auritus</i>) and its potential for thermal substitution
Bibliographic record
Abstract
Diving endotherms inhabiting polar regions face potentially high thermoregulatory costs. Unless properly insulated, these animals will lose vast amounts of heat when diving in cold water, which has to be balanced by heat production. Heat generated as a by-product of digestion (heat increment of feeding, HIF) or from exercising muscles might be important in maintaining thermal balance under such conditions, as it would reduce the need for shivering thermogenesis. Recording the rate of oxygen consumption (V(O(2))), respiratory exchange ratio (RER), and stomach temperature, we studied the magnitude and duration of HIF in seven double-crested cormorants (Phalacrocorax auritus) following the voluntary ingestion of a single herring (Clupea pallasi) while birds rested in air. Conducting trials at thermoneutral (21.1+/-0.2 degrees C) and sub-thermoneutral temperatures (5.5+/-0.7 degrees C), we investigated the potential of HIF for thermal substitution. After the ingestion of a 100 g herring at thermoneutral conditions, V(O(2))was elevated for an average of 328+/-28 min, during which time birds consumed 2697+/-294 ml O(2) in excess of the resting rate. At sub-thermoneutral conditions, duration (228+/-6 min) and magnitude (1391+/-271 ml O(2)) of V(O(2))elevation were significantly reduced. This indicates that cormorants are able to use the heat generated as by-product of digestion to substitute for regulatory thermogenesis, if heat loss is sufficiently high. Altering meal size during sub-thermoneutral trials, we also found that HIF in cormorants was significantly greater after larger food intake. Based on these experimental results, a simple calculation suggests that substitution from HIF might reduce the daily thermoregulatory costs of double-crested cormorants wintering in coastal British Columbia by approximately 38%. Magnitude of HIF and its potential for thermal substitution should be integrated into bioenergetic models to avoid overestimating energy expenditure in these top predators.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| 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".