on mud flats near water, some perched on piling. Surface of tide flats - covered by tracks, perhaps largely of gulls. Zonal character --- ? 2. Steep north facing slope near Mill Valley. Heavily wooded, mainly red- wood. Zonal character - transition. Characteristic birds found here: - Chickadee, Coast jay, Olive-sided flycatcher, Western wood pewee and Western flycatcher, and California jay, (an upper sonoran form which ranges into transition). Other birds which occurred here: - Spurred towhee, Blackheaded grasshopper and Greenbacked goldfinch. (Nest observed in cedar tree near edge of town. Bird or nest probably incubating eggs. Purple finch also heard in woods at foot of slope. 3. Bare arid hill slopes above timber line. A typical arid upper sonoran region. - Vegetation - scant