Northward Summer Migration of Red-Tailed Hawks Fledged from Southern Latitudes
Bibliographic record
Abstract
With a breeding range extending from approximately 68uN in northern Canada to 8uN in Panama, Red-tailed Hawks (Buteo jamaicensis) exhibit migrations that vary substantially with latitude. Northern populations are almost completely migratory, middle-latitude populations are partially migratory, and southern populations south of 38uN are considered sedentary. Contrary to the latter widely held belief, we found that many juveniles and young adults from one population below 38uN are also partially migratory. However, unlike most birds in the northern hemisphere that migrate south in autumn, young Red-tailed Hawks from our southwestern California study area migrated north in summer to summering areas as far as 1462 km from their natal nests. Of the 5271 Red-tailed Hawk nestlings we banded in the study area and an additional 189 banded by other researchers, 205 were encountered (found dead or alive or recaptured) outside the study area. We classified 64 encountered hawks as potential migrants, most (69%) of which were encountered to the north of their natal nest (median 5 383 km). We found that juveniles and young adults banded south of 35uN in the Pacific Flyway migrated north, whereas those banded north of 40uN migrated south. Sixteen hawks from the study area equipped with satellite transmitters as fledglings migrated north (range 342-24u) in summer, up to 1388 km, and returned to their natal region in autumn of the same year. This pattern was repeated annually until they acquired a mate and territory. Our results showed that many or most young Red-tailed Hawks migrate northward in the summer, and we propose that this pattern may be a response to historical climate changes, seasonal changes in sciurid prey availability, and/or dominance of territorial adults.
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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 | 0.002 | 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) | 0.002 | 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".