The book "Postnatal Development of Two Breeds of Great Gray Wolves (Bubo virginianus)" is the result of an in-depth study by the authors, Donald Fredrik Hofmeister and Henry W. Sesker, of the process of development of two great gray wolf chicks after birth. They explore the period from birth to independent life of these majestic birds, revealing important aspects of their physiological and behavioral development. The authors provide the reader with the opportunity to immerse themselves in the world of great wolves-owls, to understand their nature and interaction with the environment. This book will be an important source of information for scientists, zoologists, ecologists, and anyone interested in the natural processes of wild animal development.