Richard Pennycuick writes:

>I don't see why it's not possible for it to be both, but I assume Stephen
>means it may not be "music" to our ears rather than to those of the avian
>recipient of the message.

Actually, I was thinking of the avian recipient as well.  As another
illustration, would we consider a public address announcement in a
department store of a sale on Beanie Babies to be music? Perhaps birdsong
is music to a bird if it's for courtship and not for warning of oncoming
cats, or whatever?

 - seb