Food Habits of the Grass Snake in Southeastern England: Is Natrix natrix a Generalist Predator?
Bibliographic record
Abstract
Generalist species are often both widely distributed and abundant. They also are often plastic in their ecology, both spatially and temporally, in response to variation in resources. Here, we study the food habits of the widespread European Grass Snake, Natrix natrix, in Kent in southeastern England. As elsewhere in their range, Grass Snakes at our study site mainly ate anurans (63%); however, small mammals also were fairly common in the diet (25%) and fish (10%) and birds (1%) were taken occasionally. About 65% of prey eaten by snakes were swallowed headfirst, but orientation of prey during ingestion varied among prey types. Although anurans are the major prey of Grass Snakes, the predominant species in their diet varies geographically, presumably in relation to availability; at our site, the most frequently eaten species (63%) was the introduced Marsh Frog, Rana ridibunda, which is very common and possibly influences abundance of snakes. We obtained few data on feeding habits of small snakes (< 400 mm SVL) but found anuran prey in the smallest snake in our sample; other prey types were eaten by larger snakes and therefore presumably are added to the diet as snakes grow. Maximum size of prey increased with snake size, but large snakes nonetheless continued to eat small prey as well. However, because Grass Snakes are sexually dimorphic (females larger), such size effects may be confounded with sex effects. Snakes had food in their stomachs less frequently in midsummer than they did in early and late summer. Nonetheless, even after adjusting for such seasonal variation, gravid females contained food less frequently than nongravid females. Thus, gravid females of this oviparous species apparently exhibit an anorexia similar to that seen in pregnant females of many viviparous species.
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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 | 0.000 | 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) | 0.000 | 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".