Seasonal Diet Variation in Thirteen-Lined Ground Squirrel (Ictidomys Tridecemlineatus) in Southernwestern Michigan
Bibliographic record
Abstract
Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) are omnivorous ground squirrels that range from Texas to Alberta and from Michigan to Utah. The amount and type of both animal and plant matter in their diet may vary both geographically and seasonally. The present study was motivated by prior work, based on δ13C analysis of incisor enamel of thirteen-lined ground squirrels from a colony in southwestern Michigan, suggesting that these animals underwent a pronounced, late-season shift in diet from predominantly C3 to C4 plants. However, this inferred dietary shift was not directly demonstrated. Here, I tracked diet of thirteen-lined ground squirrels in southwestern Michigan from June to October 2018 using fecal samples deposited by animals when live-trapped; squirrels were then released unharmed. In addition, I collected and identified voucher plant specimens at the field site. Microhistological and isotopic analyses of fecal samples documented two primary seasonal shifts in diet. First, the microhistological data indicated a sharp decrease in arthropod consumption as summer turned to fall; this decrease correlated with the overall decrease in δ15N and 1/C:N (carbon:nitrogen; a measure of trophic position and degree of carnivory). These observations were consistent with a shift from a protein-rich early summer diet rich in arthropods to a fall diet with less protein. Secondly, the microhistological data demonstrated a dramatic late-season increase in consumption of grass seeds and glumes, which mirrored a sharp increase in δ13C. Both of these data sets indicated a shift from primarily C3-plants to a mixed or primarily C4-plant diet in August, with a C4-rich diet continuing into October. In summary, my study a) documented a previously unknown shift from high to low use of arthropods, a pattern that is contrary to findings of prior studies, and b) confirmed the late-season shift from C3- to C4-plants previously inferred from enamel isotope data.
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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 | 0.000 | 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) | 0.001 | 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".