There are seven baby bunnies that belong to Bill. Their names are Fuzzy, Whitey, Brownie, Spotty, Black Ears, Cotton Tail, and Herbert Nenninger. He also owns their mother (Ma Rabbit), whose burrowing abilities are important in several episodes. They are all voiced by Frank Welker.
In Curious George's Bunny Hunt, Herbert Nenninger is a brownish-tannish color. In Bee is for Bear, he is white. However in Curious George's Bunny Hunt, the only white bunny is Whitey.