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. 

More info and transcript at BirdNote.org. 

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