Bluebird Manufacturing Co. was apparently a manufacturer from Philadelphia, though the Ukulele I have seen was definitely made by Regal. I have seen Oscar Schmidt and other similar usual suspects as a suggested maker too? I read the firm started in 1925 and went on to possibly the 1950's; though I have not seen anything post war. They sold Ukuleles and Banjoleles under this branding. along with Guitars, Mandolins and Banjos. 

The Banjos I have seen, whilst having a lot of similarities to other makers have some unique individual characteristics too, like the metal resonator with the round central hole, the offset headstock and the space at the bottom of the fretboard.