A freshwater marsh once surrounded Bloody Island before land reclamation efforts began in the late 19th century. Marshes around Clear Lake supported native plants including tules, rushes, sedges, and cattails, along with cottonwood, willow, and elderberry, and a dense expanse of tules and willows once extended from this area to Lakeport. These marshes flooded in winter and spring and dried in summer, but that seasonal cycle and the ecosystem it supported were disrupted when land speculators and ranchers drained marshes to create agricultural fields. Native fish of Clear Lake included rainbow trout, thicktail chub, Clear Lake splittail, Sacramento pikeminnow, Sacramento sucker, Sacramento perch, Sacramento blackfish, Clear Lake hitch, tule perch, and prickly sculpin; of these, only the blackfish, hitch, perch, and prickly sculpin are still common, while many fish now common in the lake, including bass, carp, catfish, crappie, and bluegill, are non-native introduced species. Clear Lake also supports resident birds such as mallard ducks, wood ducks, northern shoveler, green-winged teal, American coot, double-crested cormorant, great blue heron, osprey, Clark's grebe, and western grebe, and because it lies along the western margin of the Pacific flyway, it also receives migratory birds including Canadian geese, American white pelican, canvasback, ruddy duck, northern pintail, common merganser, hooded merganser, pied billed grebe, and greater scaup.