Changes in the geomagnetic field has little effect on the overwintering range of Eastern North American fall migratory monarch butterflies (Danaus plexippus), indicating a lack of an innate magnetic map sense for navigation
Bibliographic record
Abstract
Abstract BackgroundIndividuals of many species that perform annual long-distance migrations are capable of stopping at specific overwintering destinations, despite having not been there before. The iconic monarch butterfly (Danaus plexippus) and its annual long-distance fall migration is a famous example of this phenomenon. During the fall, Eastern North American monarch butterflies use various compass mechanisms to properly orient their flight southwards, in order to leave their summer breeding grounds in Southern Canada and the Northern United States, and reach their overwintering sites in Central Mexico. It remains a mystery, however, how monarchs locate and stop at these specific, consistent overwintering sites, especially since these individuals are on their maiden voyage. MethodsWe test the hypothesis that fall migrant monarchs locate these overwintering sites by using an innate, inherited map sense based on sensing and responding to specific geomagnetic signatures that are correlated with the overwintering sites. Using a natural displacement approach, we examined if the locations of overwintering sites and the abundance of monarchs at them, changes with the natural shift of the Earth’s magnetic field over time (2004-2018).ResultsWe found that despite the natural displacement of the geomagnetic field over the years, the locations of the overwintering sites and monarch abundance were unaffected. For example, fall monarchs continued to overwinter at the most southern sites in Mexico, even when the geomagnetic coordinates associated with these sites would have shifted north due to the natural shift of the Earth’s magnetic field, placing these sites significantly outside the range of the overwintering area.ConclusionsOur results suggest that monarchs do not employ a map sense based on geomagnetic cues for finding their overwintering sites, and might instead use other mechanisms or strategies for locating them (potentially using localized sensory cues) once they are near or have arrived in Central Mexico. We suggest that future work should now focus on understanding what these cue parameters are, in order to inform conservation efforts that are aimed at protecting the threatened monarch butterfly and preserving its annual long-distance migration.
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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".