Eight quite clever stories introducing Verity ``Birdie'' Birdwood--``an odd little person who set herself up...as some sort of amateur detective.'' The incisive, pragmatic, and frequently tart Birdie--scourge of criminals from one end of Australia to the other--recalls the first murder she witnessed on the Christmas Eve she was 14 (``Forbidden Fruit''), then, in later years (``Death in Store''), solves the murder of a department store Santa and his helper. In between, she and her friends Toby, an overweight, lonely copper, and the lively Kate and her young daughter Zoe grapple with a sliver of poisoned quiche (``Ladies' Day'') that brings a wandering husband to heel; a wife who expires on a beach towel in full view of all the bathers (``Death Warmed Up,'' the best tale here); and two fatal identity switches (``Flashpoint'' and ``Death in Ruby''). A poignant ``Rabbit Killer'' finds Birdie wrestling with a disgruntled farm family, and the short ``Roses for Do- Hoppy'' places her on a street corner where a newspaper-seller, a flower vendor, and a hotel doorman collide. A notch or so below Christie and John Dickson Carr at their best--but gently written puzzles for ratiocination fans of a cozy bent.