Some birds stash unopened seeds for use later. But how do they know which seeds are worth the trouble, before expending the energy to open them? A team of scientists from South Korea and Poland may have an answer. As part of a series of experiments, the scientists observed the behavior of Mexican Jays presented with peanuts in their shells. The research team documented the birds shaking nuts in their beaks to assess the weight and possibly listening for the nuts rattling. In other words, jays use the same types of sensory cues that humans do when choosing a melon in the supermarket.
Jays Identify Good Nuts by Shaking Them
Written by GrrlScientist
This is BirdNote.
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? [Mexican Jay call and mechanical sound http://macaulaylibrary.org/audio/96005]
Recently published 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 weighed less.
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 use the same kinds of sensory cues that we do when we choose a melon in the supermarket.
For BirdNote, I’m Michael Stein.
Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Mexican Jays  recorded by William W H Gunn.
BirdNote’s theme music was composed and played by Nancy Rumbel and John Kessler.
Producer: John Kessler
Executive Producer: Dominic Black
© 2015 Tune In to Nature.org August 2015 Narrator : Michael Stein
ID# MEJA-01-2015-08-11 MEJA-01