When Common Loon chicks first hatch, they are covered with down and look like sooty black puffballs. These feathers are pushed out when the loons are 10 to 14 days old by a second plumage of brownish-gray down feathers. When the young are about a month old, these feathers start to be replaced by juvenal contour feathers. By the time the young loons are 10 or 11 weeks old, their down feathers are mostly gone and their juvenal plumage is nearly complete. This plumage is very similar to the winter plumage of adult loons. You can tell the difference between the two by the whitish-gray tips of the juveniles’ feathers, which the adults lack. (Pictured juvenile loon is about seven weeks old, showing remnants of the second down plumage.)
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