Avian density and diversity in forest gaps and closed canopy areas of Golestan National Park

The aim of this study was to investigate the density, diversity, and distribution of birds in canopy closed and gaps areas of the forest in Golestan National Park in 2015. Birds and environmental variables were recorded within a 25 m radius of each of 122 sampling points. To determine the bird species density and association between environmental variables and bird community, distance sampling method and Redundancy analysis was performed, respectively. To determine the association of bird diversity indices with environmental variables, the Redundancy analysis (RDA) was performed. In the period of the study a total of 216 birds, 14 species, were recorded. In gap area, Great tit (Parus major) , Blue tit (Parus caeruleus), and Robin (Erithacus rubecula) had the highest density, and Black woodpecker (Dryocopos martius), Wren (Troglodytes troglodyte), and Spotted flycatcher (Muscicapa striata) had the lowest density. In canopy closed area Great tit, Blue tit, and Robin had the highest density, and Blackbird (Turdus merula), Coal tit (Parus ater) and Spotted flycatcher had the lowest density. The values of 2, 0.5, and 0.6 were respectively recorded for the number of dominant species (N2), Shannon diversity index and Camargo evenness index. These indices had the highest values in canopy closed areas. The results of this study highlighted the importance of canopy closed areas for conserving and enhancing of birds especially in Golestan National Park.