But in the books, they don't need wands to transform into animals. They only need the wand when they become animagi for the first time, when they do this sort of spell, wich took James and Sirius 3 years to figure out. It's very difficult to do it, I've heard
But they don't need wands to transform. But I wonder where Pettigrew's wand where when he was transformed... Maybe I bought/stole a new one, after he had returned to Voldemort?