Habits as COMU. More likely to come to shore in winter. ID: Tricky, and made worse by individual variation in bill size and head pattern. Many features intermediate between RAZO and COMU. From COMU by thicker neck, shorter bill (overlap), white line at gape (adults), darker upperparts, dark head pattern and often dingy throat (nonbr), and clean white flanks. Trailing feet often visible on swimming birds.