Also known as: Great Northern Diver
71-91 cm (28-36") Most common and widespread loon. Forested lakes and rivers. Large diving bird with a stout dagger-like bill that is held horizontal.
Summer: Black head; black bill; barred black-and-white neck ring; checkered black-and-white back.
Winter: dark upperparts; white underparts; pale bill; white triangular indentation at midneck.
Song: various vocals add to the mystique of the North; yodeling and maniacal laughter; tremulous "ha-oo-oo" often given at night.