Book Description: Illus. in full color. "Big Bird, Ernie, and Bert explore the ever-changing zoo with Willie, a new friend whose mother works there. Bert has already visited the zoo, but Willie shows him that one can always find something different to enjoy there. In her introduction to the text, the Bronx Zoo's curator of education lists ways to recognize changes at the zoo. The excellent illustrations are realistic and detailed enough to reinforce a story that children will enjoy."--Science and Children.