Edge effect on density and diversity of bird community in Golestan National Park

This study focuses on the different edge types affecting bird density and diversity in Golestan National Park. Birds and environmental variables were detected within a 25 m radius of each of 73 sampling points. To determine the bird species density and their association with environmental variables, distance sampling method and canonical correspondence analysis was performed respectively. To determine the association of bird diversity indices with environmental variables, the canonical correspondence analysis were performed. Red breasted Flycatcher and Chaffinch, and Nuthatch had the highest density in rangeland and agriculture edges respectively; meanwhile, Chukar and Crested Lark, and Pheasant had the lowest density in river and road edges respectively. At the road edge, Song Thrush, Jay, Syrian Woodpecker, Treecreeper, Black Woodpecker, Coal Tit, Great Tit, and Blue Tit had the positive correlation with the number of trees with dbh 20-50 cm, the number of trees between 10 to 20 m in height, canopy cover, litter depth, and the number of trees with dbh more than 100 cm. Moreover, at the agriculture edge, Nuthatch, Long-tailed Tit, Lesser Spotted Woodpecker, Great Spotted Woodpecker, and Common Redstart showed positive correlation with stone cover, the number of trees with dbh 50-100 cm, and the number of trees with height of less than 10 m. The number of dominant species (N2), Shannon diversity index, and the number of species had the highest values at the road, agriculture, river, and rangeland edges respectively. In contrast, Camargo evenness index had the highest value at the rangeland, river, agriculture, and road edges respectively.