Seasonal effects of various ecotones on the avian community of adjacent riparian woodlands on the River Danube
In 1992 and 1993 six test areas were chosen along the banks of the Gießgang, an irrigation system in the northern backland of the reservoir of the Greifenstein hydropower station. Each area comprised 200 m of homogenous river bank and extended 60 m into natural riparian woodland. Paired areas of the same ecotone type were as follows: (A) trees border on the water directly; (8) there is a bush-line between the trees and the water; (C) the same as type B with a reedbank in front of the bushes. The birdlife of the six areas was investigated all the year round. The results showed when and how they used the structures of woodland and ecotones. The test areas with type C ecotones contained the most species and individuals. In 1994 three new test areas were investigated, in which the three different ecotone types were situated in front of hybrid poplar forests with a simpler habitat structure than natural riparian woodland.