Edge Effect On Bird Species Diversity And Guild Structure In Thousand Island Lake

To understand the edge effect on island bird species diversity and guild structure, we selected14islands with three different area gradients(<1ha,1-5ha,>5ha) in the Thousand Island Lake and the bird survey lasts from November2011to January2012and from April to June2012. We used point count method and mist-net during the investigation, and then analyzed the structure of bird guilds, species diversity and richness in different distance gradients from edge of the islands. The results showed that:(1) There was more guild number in breeding season than winter, and the guild number varied with the change of distance gradient in two seasons. In breeding season, the guilds had more species number than winter. Cavity-insectivorous guild, canopy-omnivorous guild were mainly gathered in0-50m distance gradient. Shrub-insectivorous guild, canopy-insectivorous guild and shrub-omnivorous guild were mainly gathered in25-75mdistance gradient. Thus, we suggest that edge distance will affect bird guilds structure.(2) Species diversity, species richness peaked in25-50m distance gradient in breeding season, and peaked in0-25m distance gradient in winter. The patch size, patch shape, light intensity, wind strength, vegetation structure or other factors will directly or indirectly impact on bird community. Which led birds to different variation trends in breeding season and winter, and gathered birds in different distance gradients.(3) With the increase of island area, the species diversity, richness in25-50m distance gradient in breeding season increased significantly. But in winter, there was no significant variation in all distance gradients. Considered about edge distance and island area, there was a significant interaction between them in breeding season We suggest that edge distance and island area play important roles on bird diversity. And the strength of edge effect depends on island area.