Aaah. Dys beat me to it. I had that Jan Peerce record. I also had a friend who told me once that if I ever played that record again when she visited that would be the last I saw of her. I thought it was touching.
But to clear this matter up once and for all:
Dictionary of Etymology: The phrase, bluebird of happiness is from the 1909 play romance "l'Oiseau bleu," lit. "The Blue Bird," by Belgian dramatist and poet Maurice Maeterlinck (1862-1949).
An internet comment:
The Blue Bird of Happiness is so elusive, but once 
one flies by you the memory of that joy remains forever.
Bluebirds generally seem to elicit positive responses, but the popular association with happiness seems to have coalesced in a 1908 play by Maeterlinck. Two children set out searching for happiness in the form of a blue bird, and travel far, only to find it back in their own home.
The birds themselves suggest more.
Reappearing across time and space, bracketing a tortured year, their flight is not deterred by terror. They remain on schedule. Yet they are migrants, and must be at home wherever they are, even in a patch of park between the breeding and the winter grounds.
And if you'd like to hear Bluebird of Happiness accompanied by tweeting:
http://www.southcom.com.au/~seymour/kaufman/happiness/bluebird.htm
