They were in breeding plumage, diving and feeding along the bridge along I-90. Most of the lakes along I-90 and into Northwest Washington are still frozen. A loon whose skin came in contact with that frigid water would quickly die of hypothermia. Fortunately, loons can keep their skin dry even when diving as deep as 60 meters down. Although the loon's skin is protected by feathers, its beak, eyes, legs, and feet are bare.
Loons generally stay on saltwater until age three or older.
Exceptions can be found in nature, but it isn't common for young loons to migrate. That's just one difference between young loons and older ones. Another difference is their timing for growing new feathers. Older adult loons grow new feathers in February and March. They molt their body feathers and their primary wing feathers, which are the ones most critical for flight.