Thumper is a rabbit and the fun-loving best friend of Bambi who tries to help him in any way even if physically unable to. He can also be a bit of a smart aleck. Thumper was born, possibly on August 28, to Papa and Mama Bunny. He was one of at least nine children, most of whom were girls. It is unknown if Thumper was the name given to him at birth or a nickname received later in life.

Source: Fandom