Coast of San Mateo county showing transect lines and number of murrelets seen with 300 m of survey vessels, 1986-1994. A small circle = 1 bird, medium circle = 2-5 birds, and large circle = >5 birds: star designates the breeding area (from Ainley et al. 1995b). Shading indicates region of coldest water. Upper left cell in A indicates details on breeding area and physiography of the region.