Why are the Common Loon's eyes red? The red is caused by a pigment in the retina that filters light when loons dive beneath the water's surface and allows for sight.

What color are loons?

In summer, adults have a black head and bill, a black-and-white spotted back, and a white breast. From September to March, adults are plain gray on the back and head with a white throat. The bill also fades to gray. Juveniles look similar, but with more pronounced scalloping on the back.

Why do loons change color?

Molting Adult

At the end of the breeding season, adult loons begin their molt. During this time, they transition from their striking black-and-white breeding plumage into their gray-and-white winter plumage. This transition typically begins with the feathers surrounding the bill.