Lunda cirrata [now Fratercula cirrhata] - Tufted Puffin

Like other puffins, tufted puffins have vastly different breeding and winter plumage, along with horny coverings on the bill during the breeding season.

Bulletin de la Societe Zoologique de France. 1879.

Fratercula corniculata - The Horned Puffin

The “horns” of the horned puffin are the fleshy protuberances above the eyes. Check out the parts of the face in Fig. 4 (the bill plates on the beak and the horns around the eyes). Those are grown during the breeding season and shed each year.

Bulletin de la Societe Zoologique de France pour l’Annee 1879.

Birds of New York State. 1919, from N.Y. State Museum.