Abstract <p>The population structure of snow sheep groups in the Kodar Ridge is characterized based on data from trail cameras and visual observations. The population range is isolated and limited to this mountain range. The studies were conducted after the establishment of a national park within a part of the Kodar snow sheep range (in 2018). The main observations were made in the central, most important part of the range in the Srednii Sakukan and Apsat river basins, both in the national park and in the adjacent territory. On average, the ratio of adult females to young of the year to yearlings to young males to mature males in July–September on summer pastures used by females is 10 : 9 : 4 : 3 : 1. A significant number of males stay in summer in areas outside the pastures of females and young animals. The fertility of the Kodar sheep during the study period is higher than that noted in the 1990s. For one adult female of 2019–2024 in the first 2–3 months after lambing, there were 0.87 young of the year and 0.44 yearlings. High fertility also confirms the optimal structure of the studied groups of Kodar snow sheep. Information is obtained on the timing and characteristics of the seasonal change of habitats, with the exception of the winter period. On summer pastures, the population is characterized by low herd size: 3.0 for groups of females, 1.3 for males, and the same for separated yearlings. Over 6 years of observations after the creation of the national park, the herd size indicator did not change significantly, and changes were observed in the sex and age structure associated with an increase in the proportion of yearlings and young males.</p>