The effects of habitat fragmentation on bird communities in Hyrcanian forests (Case study: Gorgan Township)

Habitat destruction is one of the main factors threatening species so that until 1980 about 30 percent of species became endangered because of degradation and destruction of wildlife habitat. Birds were surveyed in four different patch sizes ( < 1 ha, 1-10 ha, 10-25 ha and > 300 ha). Environmental variables, including forest cover type, characteristics of the structure and complexity of vegetation and those of landscape as well as the number of birds were recorded within a 25-m radius of each of 74 sampling points. Results showed that habitat variables including vegetation type, number of snags, number of logs, number of trees with dbh 0- 20, 20-50, 50-100, 100-300 cm and basal area were the most important variables affecting the presence of birds in the study area. The results of this study highlighted the importance of forest patches and their attributes in conservation and enhancement of bird’s habitat as well as in conservation of biodiversity of forest ecosystems.