Summer bird populations of burnt bog-forest land of the Kerzhensky Nature Reserve ten years after wildfires (Central Volga region, Russia)

Abstract

The bird population was monitored during ten years in the Kerzhensky Nature Reserve damaged by severe wildfires in 2010. In the burned territory 126 bird species (120 species in the breeding season) were noted, for which weighted averages of bird abundance were calculated. It was noted that the number of species was increasing gradually in the breeding season. The birds of forest edges and of dry valleys appeared already during the second post-fire year, but their abundance increased only in the third-fourth year. The bird population abundance has increased almost 2 times in the breeding season over ten years, while it has not increased significantly in the post-breeding season. The total biomass and the transformed energy, on the contrary, decreased especially in the post-breeding season. During the first six years Fringilla coelebs Linnaeus, 1758 was the absolute leader at the abundance, and its co-dominant was Anthus trivialis (Linnaeus, 1758), and in last two years Phylloscopus trochilus (Linnaeus, 1758) was the leader. The share of the leaders in the breeding season gradually decreased, and the species diversity and the alignment grew. The birds fed in the breeding season mostly on the soil surface. The share of shrubby species increased by two times a couple of years after the wildfires, and the share of crowns birds increased after another four years. The similarity of the ornithocomplex of the burnt territory in the first and last two years of the research amounted to only 0.63 units (the Sorensen-Chekanovsky index).