Here's a version I heard sung live (once) and loved it so much I remembered the first verse (but not the second):

If all the young ladies were blackbirds and thrushes,
    Sing clearly, sing clearly, oh fly not from me;
Not a thrush would I part with for ten golden guineas,
Nor barter a blackbird for a pearl of the sea.
I would love them so dearly,
So late and so early,
And ah, they'd sing clearly
At dawn, eve and day.

Would love to hear from anyone who knows this version, to get the complete lyrics. (rfdarsie@gmail.com)