Cape Disappointment is a diverse area at the mouth of the Columbia River, consisting of cliffs and headlands, exposed sand flats and beaches, tidal sand flats, and 1,200 hectares of open marine waters. It includes Fort Canby State Park except the developed area around the campground, the Cape Disappointment and North Head lighthouses, and the marine waters extending southward to the state line and westward three kilometers into the Pacific Ocean. The steep, rocky cliffs of the headlands form a relatively secure nesting area for marine birds.
This site is important because it contains a marine bird-nesting site in close proximity to good foraging habitat. The cliffs near the lighthouse on the cape support these nesting birds: 96 Brandt's Cormorants, 240 Pelagic Cormorants, 12 Pigeon Guillemots, and 12 Glaucous-winged Gulls. The marine waters in this area support thousands of feeding seabirds, including shearwaters, gulls, terns, and significant numbers of Common Murre, a candidate for listing by the Washington Fish and Wildlife Commission as a threatened species. Fort Canby State Park is considered a migrant trap with an exceptional number and diversity of landbirds during spring and fall migration.
Disturbance of birds during nesting season by recreational boating and by aircraft is a critical problem. Overfishing and pollution of the water by ship-borne contaminants are secondary threats.