A cat, a blue jay, and a red-eyed tree frog

An odd combination of animals, but they're the amusing main characters in The Familiars by Adam Jay Epstein and Andrew Jacobson.  Aldwyn, a scrappy alley cat, is on the run after stealing some fish, and he ducks into a store that's filled with animals.  A pet store?  Not quite - these are magical animals that are sold as "familiars" to wizards-in-training.  Before Aldwyn knows it, he's scooped up by Jack and heading for quite a bit of adventure.  Jack's two fellow apprentices have familiars of their own, of course: Skylar, an uppity blue jay, and Gilbert, a very funny (and clueless) tree frog.  When the three magicians are kidnapped, it's up to their familiars to save them....except that Aldwyn hasn't exactly told the others that he has no magical ability whatsoever.  Lots of action and plenty of humor - I wasn't surprised to learn that movie options have already been picked up.