Baby Big Bird appears in the Sesame Beginnings video and book series.
In character existed for marketing purposes, back at least to 1991, when Jean-Guy White was commissioned to construct a character. In 1993, Meet the Sesame Street Babies was the first book appearance of Baby Big Bird; at least four other Sesame Babies books featured the character as an illustration or photo puppet.
Outside of Sesame Beginnings, Baby Big Bird had also made appearances in "Elmo's World: Babies" and in a Sesame Street resource video via photos. The video also shows an aged photo of Granny Bird as an infant (a doctored image of Baby Big Bird).