At the beginning of the theme have each child choose an animal to adopt. You can have picture cards available for them to choose from. Give them the picture along with a form to fill out as they learn more information about the animal. Either send the form home for the parents to do with them or use them in school to fill out as you learn about animals in class.
Prepare a bulletin board with cages. Children can make zoo animals to hang on the bulletin board throughout the month. To can start by putting actual photos of animals on the board that the children can replace with their own drawings and creations until it becomes totally child-created.