Using unmanned aerial vehicles to count the numbers and monitor the condition of the Baikal seal (Pusa sibirica Gmelin 1788, Phocidae)

To develop a method for monitoring the condition of Baikal seals (Pusa sibirica Gmelin 1788) and to count their numbers in summer haul-outs using an unmanned aerial vehicle (UAV) in July–August 2020 and 2021 on the islands of Tonkiy, Kruglyi and Dolgiy (the Ushkany Islands archipelago), visual surveys and surveys with UAVs were carried out. The maximum number of seals observed in 2020 was 3467, in 2021 it was less, 1295, and their total number in 2021 was also less than in 2020. During both years of observation, the number of seals in the haul-outs gradually decreased, which might have been due to the wave level on the lake. Contrary to the popular belief the largest seal haul-out being on the Tonkiy Island, the greatest number of seals was recorded on the Dolgiy and Kruglyi islands. Recommendations for the use of UAVs are given, these can also be useful in developing the rules for tourists visiting the national park.