Often described as a flying football, this species is chunky, thick-necked, rounded, and evenly shaded over most of its body. It is sooty charcoal gray on the back, head, and breast. The belly and undertail vary from medium gray to near white. The bill is fairly stout, mostly dark with a pale area at the base of the lower mandible. The eye is pale with a small white spot over the forward end. Cassin's Auklets are usually observed at sea from a boat; they visit nests on land only at night.

Length: 23 (cm) Wingspan: 38 (cm)

Voice:

Croaking sounds near nest site.

Habitat:

Open ocean; nests in burrows.

Behavior:

Colonial. Excavates burrows at night and arrives after dark to feed chicks. Not usually seen from land.

Feeding:

Eats crustaceans and small fish; stores food in an internal pouch to carry back to nest.