Abstract <p>The purpose of this study was to establish the order and nature of the development of the Baikal seal (<i>Pusa sibirica</i> Gm.) in different areas of the rookery on Dolgii Island, Ushkan’i Islands, Lake Baikal, also determining whether there was a correlation in the number of animals in different rookeries, as well as the time and daily dynamics of their development. We also wanted to identify differences in the functioning of rookeries subject to anthropogenic influence vs. rookeries where it was absent, and to assess the ecological capacity of all rookeries on Dolgii Island. The material for the present study were still images obtained using eight camera traps monitoring different sections of the coast on the northern side of the island. The cameras automatically took photographs of the shore every 3–4 h during May to June 2022. The study showed that Baikal seals, a few days after the northern part of the lake had been completely cleared of drifting ice, almost simultaneously started approaching the island in all rookery areas. Within three days, a few haulouts were formed. In early June, the numbers of seals were rapidly increasing everywhere, but the natural dynamics of the numbers were interrupted on June 7 by the appearance of an extraordinary disturbance factor (a boat) at the rookery. A significant part of the seals left all rookery areas and only after 1–2 days did the numbers of seals begin to recover at the expense of other individuals. In the second ten days of June, the numbers of seals in five areas fluctuated greatly, remaining 2–3 times lower than the initial one, and in the third ten days it dropped even more. In the other three areas, the dynamics were somewhat different. This to be explained by the insignificant ecological capacity of these areas, which is an order of magnitude lower than that of the first five. The numbers of seals in June 2022 in the areas differed significantly, since the area and nature of the substrate available to the seals were not the same, but there was a close positive correlation between the numbers of seals in neighboring areas. In all rookery areas, regardless of their ecological capacity, close daily dynamics of the numbers of seals were noted, this indicating the actual existence of a certain order of seals coming onto land during the day (seals can be present at the rookery all the day round). We assessed the ecological capacity of each site (they totaled 2400 individuals) and, taking into account the unexplored locations, the possible capacities of all rookeries on the northern side of Dolgii Island could be estimated at 2600–2700&#xa0;individuals. No differences in the behavior of seals in rookeries that were subject to anthropogenic influence vs. rookeries where it was absent could be revealed, since the behavior of Baikal seals in small and large haulouts is apparently not the same.</p>