The distribution of birds in the park varies between the life zones of the park, which is highly dependent on the elevation. The lowest areas of the park (below 3,500 feet/1,066 meters) are characterized by mature forests of Douglas-fir, western red cedar, grand fir, and western hemlock. This forested zone provides suitable habitat for Northern Spotted Owl (Strix occidentalis caurina), and Marbled Murrelet (Brachyramphus marmoratus marmoratus). Many other birds occur in this zone which are seasonal visitors or year-around residents. The next zone of the park is from 3,500 to 5,000 feet (1,066-1,524 meters) and has mixed forests of western white pine, western hemlock, and Pacific silver fir. Weather, food sources, migration, and breeding season affects the timing and species of birds found in this zone.