Imagine that it's in the middle of an exceptionally dark night. You're lying in
bed, kept awake by a loud drip coming from the bathroom down the hall. Assuming
that you don't want to turn on the lights because it might wake your
housemates, which of your senses would you use to find your way to the
bathroom? Well, hearing for one, since the sound of the drip will certainly
guide you along. You'll also use your sense of touch, as you feel your way down
the hallway. Your sense of vision will also come into play, perhaps letting you
see a spot on the floor illuminated by a distant streetlight.
The point is, you would rely on more than one sense to find your way. It's
exactly the same for animals that migrate. A bird, for example, may use smell
to follow a familiar odor, touch to gauge its speed and the speed and direction
of the wind, and vision to look for familiar landmarks and to locate the sun or
Animals on the move may use other means to navigate, too—ways that humans
will never get to experience. Some migrating birds use an internal compass that
senses the Earth's magnetic field. Dolphins and other cetaceans use
echolocation to navigate in nearby areas, and possibly in long-distance
migrations, too. And the salmon uses a sense of smell that is far more acute
than our own.
In the following activity, you'll take on the role of a salmon. Your goal will
be to move from the open ocean to a specific location in a stream far inland,
using only your sense of smell. Will you find your way using only one sense?
Let's find out.