A compass says which way to go; a map clue says roughly where you are. Migrating birds may get both from magnetic cues. đ§
Bird navigation
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Inclination is the fieldâs angle to the ground. Declination is the angle between magnetic and geographic north. Researchers tested them as location clues too.
Bird navigation
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Adult Eurasian reed warblers shifted their mean heading 151° after an 8.5° declination change, as if displaced.
Bird navigation
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A virtual-displacement test changed inclination and declination, not field strength; birds shifted as if correcting for location. Magnetic cues can map as well as point. đ§
A compass cue says which way. A map clue says roughly where. Swipe for the magnetic clue in migrating birds. đ§