SkarpHow Birds Navigate During Migration
Three foundation-level audio lessons explore how migrating birds find direction, estimate position and combine inherited programs with learned environmental cues. The series introduces celestial compasses, Earth’s magnetic field, map-and-compass navigation and the experiments scientists use to investigate these abilities.
The first lecture plays free — no account needed.
Course Content
3 modules · 16 min total
Sun, Stars and Earth’s Magnetic Compass
Discover how birds obtain direction from the Sun, rotating star patterns, polarized light and Earth’s magnetic-field inclination—and why these cues work more like several backup compasses than a single built-in GPS.
Knowing Direction Versus Knowing Position
Learn the difference between a compass that supplies a heading and a map sense that indicates location. Follow simple displacement experiments showing how some birds use magnetic gradients, odors and familiar landmarks to correct their route.
How Birds Combine Instinct, Learning and Changing Clues
Explore how inherited migratory directions guide young birds, how experience can improve route correction, and how birds recalibrate conflicting celestial and magnetic cues when clouds, winds or unfamiliar terrain make navigation difficult.
Read the Textbook
Read every chapter for free, right here in your browser.
A compass is not a GPS A migrating bird must solve two different problems: Orientation: Which way should I fly now? Navigation: Where am I relative to a destination?
The Sun, stars, polarized skylight, and Earth's magnetic field can provide directional information. They are therefore compasses. A map-like sense would add location information, such as "I am east of my usual route." Birds combine cues rather than relying on one flawless internal instrument. If clouds hide stars, magnetic information may still be available; if local conditions make magnetic information uncertain, celestial cues can help.
The Sun compass needs a clock The Sun is a useful daytime signpost, but it moves across the sky. A bird cannot simply fly "toward the Sun" because that direction changes hour by hour. Instead, a Sun compass compares the Sun's current position with an internal daily rhythm, or circadian clock.
Study Flashcards
Key concepts from this course as flashcard pairs.
Knowing Direction Versus Knowing Position
Compass
A system that provides a travel direction or heading, such as south during autumn migration.
Map sense
A system that provides information about current position relative to a destination or route.
Inclination compass
A magnetic compass that uses the tilt of Earth's magnetic field lines to distinguish poleward from equatorward.
Virtual magnetic displacement
An experiment that changes the magnetic field around a bird to mimic another geographic location without physically moving the bird.
True navigation
Correcting for an unexpected displacement by selecting a new bearing toward a goal or normal route.