Now listen to part of a lecture on this topic in a biology class.
OK, so we sometimes see this with animals that live in parts of the world where it gets very cold in the winter.
For example, in the northeastern United States,
there's a species of squirrel that does this.
This squirrel, like many species of squirrel,
loves to eat nuts;
nuts are one of its primary sources of food.
Now, nuts are very difficult to find in the winter,
but in the autumn, they're lying all over the place,
because that's when they fall from the trees.
So what this squirrel does is, in the autumn,
it spends a lot of time finding nuts.
After it finds a nut, it
prepares it-it takes off the outer shell, and cleans it.
This preparation may in some way help preserve the nut
and or may make it easier to eat later on.
The squirrel then digs a little hole in the ground
and buries the nut.
In one autumn, this squirrel may bury hundreds of nuts.
But it doesn't just dig a big hole and put all the nuts in it and cover them up.
No. It digs hundreds of holes, all over the place, and it puts just one nut in each hole.
Now why would it do that?
Well, probably primarily because,
even if other animals happen to find some of the holes, some of the nuts,
the squirrel will still have a lot of other holes with nuts in them,
so it'll still have enough food to survive the winter.