There are always a few on the American eBay site and also Ron Ray........very similar Blue Birds of Happiness. I have just seen a couple listed on Australian eBay with the seller saying they didn't know the signature, so I emailed and told her.
I have seen the signature read as Wedgwood as well!! Ron Rays signature is usually smaller, neater and on the rim of the ring shaped base.
Have you seen the red Cardinals of Love stew2u2?
There are also a few larger versions of 2 birds, or one bird and a tea light holder. The base reminds me of Tweedsmuir pieces by Chris Dodds.....in fact that is how I came to know about these American ones.