Do authors and illustrators collaborate on picture books?
If you mean do they sit down over a cup of coffee and hash out the fine points–in a word, No. With the possible exception of some writers who are related to the artists who illustrate their work, the writers of picture books don’t collaborate directly withe illustrators. Many have never even met the artists who have illustrated their work. The picture book is a blend of art and words, mediated by an editor who works with both author and illustrator, fine-tuning both art and words, separately, to serve the story.