It is inspired by an ancient Oriental mythos,
There are three blue birds. They have the most beautiful blue feather, redhead, and black eyes. They are servants of the Queen Mother OF The West (西王母). Two of them accompany the goddess all the time, and the third one is the messenger who represents the goddess.
We presuppose the blue bird in this design is the 3rd one who pass messages for the goddess, and there are magpies (symbolize joy and good luck) flying around him. So, that means the blue bird is bringing good news from the goddess.