This IBA encompasses islands in the southernmost portion of Green Bay, including Cat Island and Lone Tree Island, as well as the adjacent Bay Beach Wildlife Sanctuary (BBWS) on the mainland. The islands are mostly gravel with sparse, scattered trees and shrubs. BBWS, an urban wildlife refuge that offers wildlife viewing, interpretive exhibits, and nature education programs to the public, has lowland hardwood forest, cattail wetlands, lagoons and ponds, and restored prairie.
The islands provide nesting habitat for colonial waterbirds, including American white pelican, double-crested cormorant, and the only great egret colony in Green Bay on Cat Island. Common terns and snowy egrets have nested here in the past. BBWS is a well-known migratory landbird concentration area in both spring and fall and is a foraging area for herons, egrets, and Forster’s terns. Both the islands and the sanctuary are important for the research, monitoring, and education they have hosted over the years.