Requiem for a Birder — Robert W. Gregg

A beautiful day in June ends tragically for the Crooked Lake Birders Club when one of its members, a talented ornithologist, is gunned down during a bird hike. The sheriff considers the possibility that someone was hunting out of season, but it soon becomes apparent that the killer is one of the hikers: the victim's husband, an emotionally disturbed teenager, a bird watcher who is professionally jealous of the ornithologist, a voyeur who enjoys watching his neighbors as much as he does the birds, even an ex-CIA agent.