The monograph covers the issues of morphology, biology, geographical distribution, abundance and ecology of the bighorn sheep - a species well adapted to live in the harsh conditions of the mountainous regions of the North-East of the USSR. The description of thick-horns is given, the phylogenetic relationships of species and subspecies within the genus Ovis are considered. Ways of rational use of field resources are outlined, protection tasks are set. The book is designed for zoologists, ecologists, hunting experts.