Identification of nocturnal flight calls of Bicknell’s thrush ( <i>Catharus bicknelli</i> ) and gray-cheeked thrush ( <i>Catharus minimus</i> )
Bibliographic record
Abstract
Bicknell’s thrush (Catharus bicknelli) is a rare North American songbird that may be best detected via its nocturnal flight call (NFC) during seasonal migration. However, there is debate around whether its NFC can be reliably separated from that of the two grey-cheeked thrush subspecies (Catharus minimus minimus and Catharus minimus aliciae). We recorded NFCs in Milwaukee, US, where C. m. aliciae is the only expected taxon, and compared them with NFCs recorded in Quebec, Canada, where both C. m. aliciae and C. bicknelli occur during migration. We also recorded a small sample of NFCs in Newfoundland, Canada, where the rarer C. m. minimus breeds. Using unsupervised Gaussian mixture models, we found that the Quebec dataset can best be explained by a combination of two groups: the first group is identical to the NFCs collected in Milwaukee and is consistent with C. m. aliciae. The second group is characterised by NFCs of much higher frequencies, likely belonging to C. bicknelli. While C. m. aliciae and C. bicknelli appear to produce distinctive NFCs, calls from C. m. minimus were intermediate between these taxa. Based on these results, we provide guidelines for the detection and identification of C. bicknelli.
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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 | 0.001 |
| 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".