Which bird is the international symbol of happiness?

The international bird symbol of happiness is in fact the Bluebird.

http://www.blurtit.com/q518201.html

Somewhere over the rainbow
Bluebirds fly.
Birds fly over the rainbow.
Why then, oh why can't I?

If happy little bluebirds fly
Beyond the rainbow
Why, oh why can't I?

http://www.metrolyrics.com/somewhere-over-the-rainbow-lyrics-taco.html

The mythology of the bluebird of happiness has deep roots that go back thousands of years. Indigenous cultures across the globe hold similar myths and beliefs about the bluebird. It is a widely accepted symbol of cheerfulness, happiness, prosperity, hearth and home, good health, new births, the renewal of springtime, etc. Virtually any positive sentiments may be attached to the bluebird.

https://en.wikipedia.org/wiki/Bluebird_of_happiness

In the folklore of the French peasantry the blue bird is the symbol of happiness. It is not the more transitory happiness such as the ordinary individual experiences, but rather enduring happiness; that state of peace which will abide, as it were; unalloyed happiness.

One often hears the metaphor “the blue bird of happiness,” that elusive symbol of personal contentment and cheer...

http://www.amazon.com/Mystical-Interpretation-Blue-Bird-Raleigh/dp/1419173308