A 4,300‐year History of Dietary Changes in a Bat Roost Determined From a Tropical Guano Deposit
Bibliographic record
Abstract
Abstract Bats provide numerous ecosystem services as they pollinate, disperse seeds, and reduce insect populations. It is thus vital to monitor and understand their foraging habits. We analyzed sterols and stanols in a rare discovery of a ∼4,300‐year‐old bat guano deposit from a Jamaican cave to infer relative changes in bat feeding guilds over four millennia. In this deposit, zoosterols and phytosterols, in conjunction with δ13C and C/N data, revealed two periods of increased frugivory relative to insectivory from ca. 1000‐500 BCE and ca. 700–1900 CE. We propose two possible explanations for these intervals of increased frugivory relative to insectivory. (1) Previous paleoclimate data suggested these intervals were warmer and drier in the region, which we hypothesize resulted in reduced insect availability. We supported these inferences by comparing the same analytes in fresh guano from frugivorous, insectivorous, and sanguinivorous (blood‐drinking) bats, which showed that bats with animal‐based diets produced guano with lower C/N ratios and higher cholesterol/(cholesterol + sitosterol) ratios than those with fruit‐based diets. (2) The change in the chemical composition of the bat guano during these two periods may also be the result of a shift in the relative species composition of the bat roost that is a greater proportion of frugivorous relative to insectivorous bats during these two periods. This novel, non‐invasive method, based on the chemical composition of bat guano, tracked changes in tropical bat foraging habits extending back in time over four millennia.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 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".