Like Stranger on Big Hickory (1964) this deals with a boy who is mainly involved in a nature project, secondarily in the solution of a local mystery, and it is a much weaker story than the author's usually excellent historical adventures. Don Douglas is the crippled son of the superintendent of the preserve at Topsail Island. The boy's need for exercise encourages him to study the bird life on the island. There are some good descriptions of the island and its wildlife, but it takes an extra push to be able to interest readers in the fifty odd different species of birds that Don observes during the course of the summer. Presumably that's what the mystery was intended for, but it misses by a mile. Counterfeit evidence of buried pirate treasure on the island is recognized to be fraudulent after a series of not very convincing, not very suspenseful events. These introduce a collection of unlikely personalities on the island from Don's schoolmate, who picks on him, to a peevish gangster leader who came to dig. You can't take much stock in any of the characters or events here, but for the few boys who are really interested, the birds are fairly well presented.