A clue, and who reads it

A faint planetary clue

Magnetic sense

What does Earth feel like, if you can feel it at all?

Who uses it

• Sea turtles
• Some birds
• Spiny lobsters
• Some fish

A moving landmark

Using the Sun

If the Sun is a clock and a compass, who is reading it?

Who uses it

• Honeybees
• Desert ants
• Some birds
• Monarch butterflies

A turning ceiling

Using the stars

What is a star, if you need to go somewhere?

Who uses it

• Some songbirds
• Dung beetles (Milky Way)
• Human wayfinders

A map made of air and water

Smell and maps

Can a smell be a place?

Who uses it

• Salmon
• Honeybees
• Pigeons (one hypothesis)
• Many mammals

The last mile

Landmarks and memory

What do you keep, when the compass has brought you close?

Who uses it

• Desert ants
• Homing pigeons
• Humans
• Many territorial birds

A moving road

Waves, currents, and water

What does water remember?

Who uses it

• Sea turtles
• Salmon
• Whales
• Human wayfinders

A click that comes home

Sound and echo

Can you hear a shape?

Who uses it

• Bats
• Toothed whales
• Some birds of caves
• Oilbirds

A braid, not a single thread

Many senses at once

What happens when one clue goes missing?

Who uses it

• Almost every long traveler