Cormorants have hooked bills. Western, Clark's, and Red-necked grebes have thinner bills and show white in the wings in flight. Red-throated Loon has a thinner, upturned bill. In basic and immature plumages its back is spangled with white spots and its head and neck are pale gray, with a straighter line of division with the white foreneck. Pacific Loon has a shorter, thinner bill, a sharp line dividing the pale foreneck, and dark hindneck and no white around the eye. The Common Loon is similar in all plumages, but has a bill that is straight at the tip and a less blocky head, and an entirely dark culmen beyond the gonys. In basic and immature plumages, the Common Loon's head and hindneck are darker without a darker spot to the auriculars, and back has less pattern.