The book, How the Parrot Found its Pirate, seems like it should be a children's picture book. It's short, with well-illustrated pictures. However, using words like "plunder" make it difficult for kids to understand. The idea of attacking other ships and the images of people tied up and kept captive is also a little violent for a children's book.
The story is a cross between a picture book story and a pourquoi folktale. Telling how something came to be is often classified as pourquoi, and this book does tell the story of literally how the parrot found the pirate. Often in stories, a pirate has a parrot on board with him; this provides a tale of how that happened.
The story itself is a little far-fetched and does not contain a lesson or a moral (as often accompanies folk tales).
As such, it's hard to determine the proper audience for this book. It's above a children's book, but it's hard to use in the classroom as a teaching tool. The illustrations are very well done, but the story would be better if there was a lesson learned by the end of it.