Old Bill, the whooping crane, becomes a real creature in the reader's mind as his story progresses. The tough old bird was one of the treasured few of his kind left. And only the alertness of a warden saved him from predatory Al -- a vicious poacher. There is a December-May romance here as Old Bill meets and mates a young female, though he has many competitors among younger males. The faithful pair and their migrations to and from Canada and Texas reach a crisis when Al, released on bail, tries his luck again. This time, Al's gun explodes and he has a heart attack. His health broken, Al is rehabilitated through constructive work -- this time as photographer of birds and protector of them on the game preserve. Dependable natural history with a conservation angle.