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How might magnetic secular variation impact avian philopatry?

Abstract:
A tendency to return to the natal/breeding site, ‘philopatry’, is near ubiquitous amongst migratory birds. It has long been suggested that a magnetic ‘map’ could underpin such movements, though it is unclear how a magnetic map might be impacted by gradual drift in the Earth’s magnetic field (‘secular variation’). Here, using the International Geomagnetic Reference Field, we quantified how secular variation translates to movement in the implied positions at which combinations of different magnetic cues (inclination, declination and intensity) intersect, noting that the magnitude of such movements is determined by the acute intersection angle between the isolines in question, and the direction of one isoline’s movement relative to the other. We propose that magnetic parameters varying in a near-parallel arrangement are unlikely to be used as a bi-coordinate map during philopatry, but that birds could use near-orthogonal magnetic gradient cues as a bi-coordinate map if augmented with navigation using more local cues. We further suggest that the use of uni-coordinate magnetic information may provide a philopatry mechanism that is substantially less impacted by secular variation than a bi-coordinate ‘map’. We propose that between-year shifts in the position of magnetic coordinates might provide a priori predictions for changes in the breeding sites of migratory birds.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1007/s00359-021-01533-y

Authors



Publisher:
Springer
Journal:
Journal of Comparative Physiology A: Sensory, Neural, and Behavioral Physiology More from this journal
Volume:
208
Issue:
2021
Pages:
145–154
Publication date:
2022-02-12
Acceptance date:
2021-12-17
DOI:
EISSN:
1432-1351
ISSN:
0340-7594


Language:
English
Keywords:
Pubs id:
1226822
Local pid:
pubs:1226822
Deposit date:
2021-12-22

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