Effects of edge on the bird richness and abundance in Khoshkedaran Natural Monument, northern Iran

Increasing patch edges in natural habitats, as a result of habitat fragmentation, are a major threat for wildlife populations, especially avifaunal communities. Habitat edges provide different conditions compared to the core area which can directly or indirectly cause changes in species number, population and composition. This fact will demand a dissimilar management strategy. This study was conducted with the aim to investigate the edge effect on avifaunal richness and abundance in Khoshkeh-Daran natural monument. Bird records took place using point sampling method with infinite radius. Bird observation was recorded in mid spring 2009 daily from dawn till 9:30 am and was stopped during bad weather conditions. Vegetation cover was recorded in each 1000 m2 plot with a radius of 17.85 meters from the center where the observer was located. To study the significance of difference, between abundance and richness of avifauna among the edge and core of the patch, analysis of variance was applied. We used Canonical Correspondence Analysis to help us understand the relationship between bird communities and habitat variables. Results show a significant difference in abundance and richness along different distance from the center of the patch decreasing toward the edge. Trees and shrubs density, snags, safer environment and the presence of permanent lagoons (which will cause in tree falls) in core of the patch can be considered as reasons for these differences.