Two years after his death comes the English translation of what one is tempted to describe as Lorenz's goose song, his last formal statement on his beloved greylag geese. A lifetime of observation--which led to the important concepts of critical times in development, of imprinting and innate releasing mechanisms, of ``vacuum activity'' (in the absence of the releasing mechanism), and of the many complex variations and recombinations of behavior patterns or ``ethograms''--is summed up here in detailed descriptions of individual geese as well as in theoretical constructs. Why greylags? Lorenz says it's because when he was a child he wanted to be an owl, but reading Selma Lagerlîf's tale of wild geese convinced him that geese had more fun. Soon followed his first experience with a duckling who became imprinted on him--an event that in retrospect, Lorenz says, led to him being imprinted on birds forever. For the most part, the book is a primer on the behavior of these most social creatures (an isolated greylag is a cripple) with all the titillating tales of pair-bonding and breaking, of ardor and jealousy and hate that make critics cry ``anthropomorphism.'' Lorenz makes no bones about it: For him, geese are analogues to human behavior--their triumph ceremonies, their lamentation cries, their distance calls, and other complex vocal and motor behavior exemplify a philogenetic convergence in evolution. Like humans, geese are aggressive, struggle for rank, show ardor, bravery, and vengeance, are ever-mindful of their fellow creatures and ready to react. It's all told here in the deeply personal terms characteristic of this ardent Austrian. Gooselovers of the world, unite; this is the book for you.