This is birdnode.

Some birds stash unopened seeds for use later.

But how do they know which seeds are worth the trouble,

before expending valuable energy to open them?

Research by a team of scientists from South Korea and Poland may provide an answer.

In a series of experiments, they presented jays with ten peanut shells

that had been emptied of their nuts and resealed,

and ten peanut shells with nuts inside.

Not surprisingly, the jays preferred the shells that had nuts in them.

In the next experiment, all the shells had nuts in them,

but some had one and some had three.

This time, the jays preferred the three nut shells.

Further research suggested that the jays also preferred heavier shells

over those that had the same number of nuts in them,

but weightless.

Using slow-motion cameras, researchers saw that the birds were shaking the nuts

in their beaks to assess their weight,

and possibly also listening for the nuts rattling.

In other words, jays used the same kinds of sensory cues that we do

when we choose a melon in the supermarket.

For birdnode, I'm Michael Stein.

Did you know birdnode delivers the wonder and joy of birds directly to your inbox?

...