Changes in the diet of a recovering Eurasian otter population between the 1970s and 2010
Bibliographic record
Abstract
ABSTRACT Diet is an essential element for understanding how the Eurasian otter ( Lutra lutra ) is re‐colonizing its former range in England following a population decline observed in the 1950s to 1970s. Otter spraints from the River Glaven catchment (north Norfolk, eastern England) were collected seasonally between 2009 and 2010 from three habitat types (ponds, ‘retenus’ (small in‐stream reservoirs), and stream stretches). Feeding tactics of the otter were compared between habitat types and, using previously published data, with regard to seasonal changes since the 1970s when the species was in decline. Otter diet composition varied greatly, with predation on aquatic invertebrates, crayfish, fish, and tetrapods. Fruit seeds were also found in the spraints. Diet generally reflected habitat, with northern pike ( Esox lucius ) remains found in spraints from ponds and retenus, whereas European eel ( Anguilla anguilla ) and gudgeon ( Gobio gobio ) were prominent in spraints from stream sections. Trophic diversity was particularly high in spraints collected next to ponds. Between the 1970s and the present, crayfish, brown trout ( Salmo trutta ), cyprinids, Eurasian perch ( Perca fluviatilis ), birds and mammals increased in prominence, whereas eel and threespine stickleback ( Gasterosteus aculeatus ) decreased, with notable seasonal variations between the study periods. Otter spraints revealed few prey preferences, with only that for gudgeon being ecologically relevant. The consumption of popular sport fishes, in particular common carp ( Cyprinus carpio ), has given rise to conflicts between recreational anglers and otter conservationists, but no demonstrated preference for carp was observed in the present study. Overall, otters have increased their consumption of ‘less preferred’ (i.e. lower energetic value) food types, and because the species normally preys on the most abundant species available, this suggests declines in ‘preferred’ prey types. These dietary shifts could contribute to otter dispersal and re‐colonization of parts of its original European range where food availability may be higher. © 2012 Crown copyright.
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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".