Wrens teach their eggs...

[Dumpsterkitty]

...to sing!

Via Boing Boing

Mommy and Daddy fairy-wrens sing "food passwords" to teach their eggs to sing

Xeni Jardin at 3:06 pm Thu, Nov 8
"Superb fairy-wren (Malurus cyaneus) mothers sing to their unhatched eggs to teach the embryo inside a 'password' — a single unique note — which the nestlings must later incorporate into their begging calls if they want to get fed."

Zoë Corbyn in Scientific American, on a very unusual example of avian communication.