Changes in birds’ demographic parameters of a key ornithological territory “Tract Trekhozerki” (Minusinsk basin) with fluctuations in water level

Abstract

Today “Tract Trekhozerki” is a state natural zoological reserve of regional importance. The tract is home to over 100 species of birds, including 12 species listed in the Red Book of the Russian Federation. For five bird species, breeding information was obtained over the period from 2013 to 2018. In two species of gulls (Larus argentatus mongolicus Suskin, 1925 and Larus ichthyaetus), the abundance changes were similar: the number of breeding pairs decreased (in the second species to 0) from 2013 to 2015, and then there was an increase in numbers. The population of Ardea cinerea has decreased. Recurvirostra avosetta breeds irregularly in the tract, with 73 pairs nesting in 2018. For all these species, a decrease in the average size of masonry in years with a low water level was noted. Phalacrocorax carbo at nesting were noted only in 2013 and 2014. The changes in abundance are associated with cyclical fluctuations in the water level in water bodies: a decrease from 2013 to 2015 and a subsequent increase until 2018. This affected the availability of nests, the area of habitats suitable for nesting, and species competition. For species of birds listed in the Red Book of the Russian Federation (L. ichthyaetus and R. avosetta), the high, but not the maximum degree of watering observed in 2013 and 2018 is most favorable.