Common loon Gavia immer

Identification Tips:

• Length: 24 inches Wingspan: 58 inches
• Sexes similar
• Large diving bird with long body that rides low in the water
• Large bill is straight, tapers to a point, and is held horizontally
• Feet set far back on body, and trail behind body in flight
• Upperwings wholly dark in flight

Adult alternate:

• Black bill
• Black head
• Black neck with white markings
• White chest and belly
• Black back with white checkering and spotting

Adult basic:

• Pale gray bill
• Gray-brown cap, forehead, nape, hindneck and back
• White face, eye ring, chin, throat, foreneck and belly
• Jagged border between white foreneck and dark hindneck

Immature:

• Like basic-plumaged adult but often with paler bill and white scalloping on back

Similar species:

Cormorants have hooked bills. Western, Clark's and Red-necked Grebes have thinner bills marked with yellow and show white in the wings in flight. Red-throated Loon has a thinner, upturned bill that it carries above horizontal. 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 rare Yellow-billed Loon is similar in all plumages, but has a bill that is beveled upwards at the tip and a blockier head, and is entirely yellow beyond the gonys. In basic and immature plumages, the head and hindneck are paler with a darker spot to the auriculars, and back has more pattern.

Length and wingspan from: Robbins, C.S., Bruun, B., Zim, H.S., (1966). Birds of North America. New York: Western Publishing Company, Inc.