A field survey was made on many artificially constructed Floating Islands in Japan in order to evaluate their function as habitat for birds such as nesting or resting site. We searched each island for birds' nesting activity and observed the behavior of birds on and near the island. We also collected plant samples and identified them to make the plant species list found on each island. Floating islands were classified into four basic types according to their structure and bird usage was conpared among these types. It was found that the island type B, in which the surface of the planting material was in lebel with the water furface, was suitable as the nesting place for the several water bird species, and all types of the islands were suitable as the resting place for the water birds.
