Spatial Distribution and Abundance of the Great cormorant Phalacrocorax carbo in Buryatia in 2024

The article presents the results of a comprehensive research on the spatial distribution and abundance of the Great cormorant Phalacrocorax carbo in the Republic of Buryatia in 2024. We have monitored 21 administrative districts of the republic throughout the year using a combination of methods, including route censuses, questionnaires of the local population, and colony mapping. The study revealed complex seasonal dynamics in the population. Spring migration is characterized by a gradual movement of birds from south to north with a timing difference of up to 20 days. It has been found that the total population size in the post-nesting period reach 48.3 thousand individuals. 54.5 % breeding birds (26.3 thousand), 13.7 % non-breeding birds (6.6 thousand), and 31.8 % fledglings (15.4 thousand). During the nesting season, the population size increased by 1.5 times, mainly due to fledglings. Spatial analysis has shown a concentration of nesting sites in six districts with the highest proportion in Barguzinsky (37.2%) and Kabansky districts. Compared to 2021, the spatial restructuring of colonies is observed, including the disappearance of colonies in the Kurumkansky district and the redistribution of birds within the Barguzinsky and Pribaikalsky districts. Key limiting factors involve anthropogenic disturbance (lead to abandoned colonies), predation (destruction of up to 73 % of nests by the Mongolian gull), and food supply dynamics. The stability of the overall population size masks divergent demographic processes, including a 21.4 % decline in breeding success. The data obtained indicate the need for continued monitoring to assess long-term trends and develop conservation measures for this species.