H.J. Ruiz – Avian101

In birds, molting is the periodic replacement of feathers by shedding old feathers while producing new ones. Feathers are dead structures at maturity which are gradually abraded and need to be replaced. Adult birds molt at least once a year, although many molt twice and a few three times each year. It is generally a slow process as birds rarely shed all their feathers at any one time; the bird must retain sufficient feathers to regulate its body temperature and repel moisture. The number and area of feathers that are shed varies. In some molting periods, a bird may renew only the feathers on the head and body, shedding the wing and tail feathers during a later molting period. Some species of bird become flightless during an annual “wing molt” and must seek a protected habitat with a reliable food supply during that time. While the plumage may appear thin or uneven during the molt, the bird’s general shape is maintained despite the loss of apparently many feathers; bald spots are typically signs of unrelated illnesses, such as gross injuries, parasites, feather pecking (especially in commercial poultry), or (in pet birds) feather plucking.

The process of molting in birds is as follows: First, the bird begins to shed some old feathers, then pin feathers grow in to replace the old feathers. As the pin feathers become full feathers, other feathers are shed. This is a cyclical process that occurs in many phases. It is usually symmetrical, with feather loss equal on each side of the body. Because feathers make up 4–12% of a bird’s body weight, it takes a large amount of energy to replace them. For this reason, molts often occur immediately after the breeding season, but while food is still abundant.

Some of the birds in my backyard are undergoing molting as you’ll be able to see at the photo gallery next. Enjoy!

Northern Cardinal (M)

Brown-headed Cowbird (M)

House Finch (F)

Northern Mockingbird

Northern Cardinal (F)

Text excerpts © Wikipedia – Photographs © HJ Ruiz – Avian101