What in the World is Moulting?

Have you ever been to a friend’s house and noticed that their dog’s or cat’s fur seems to be on everything? That’s because their pet is shedding. Like dogs and cats, birds go through a similar process known as moulting. When their feathers are damaged or get too old, the feathers are pushed out and replaced with brand new ones. Unlike dogs and cats, which shed their hair continuously (like all mammals), birds moult their feathers only once or twice each year depending on the species.

cardinal - moult (small) - click

The timing and process of moulting often differs depending on the bird species; in fact, when moulting occurs it can even be different for individuals of the same bird species. Factors like time of year, location, mating, weather conditions and feather damage all play a role in when and how often a bird will moult.

One Complete Moult a Year

moult once a year
Hawks, owls and jays are examples of birds that will moult once a year

Many birds will go through one complete moult, where all their feathers are replaced once a year. These are birds like owls, swallows, jays, hawks and thrushes, just to name a few.

One Complete and Partial Moult a Year

complete moult and partial moult
Western tanagers and yellow warblers are examples of birds that will undergo one complete moult and partial moults during the year.

Some birds, like warblers and tanagers, go through one complete moult but will also lose some of their feathers before getting ready to breed (call a partial moult). After this partial moult, the males will have bright and colourful feathers to attract females.

More Than One Complete Moult a Year

more than one complete moult
Bobolinks and marsh wrens are examples of birds that will moult more than once a year.

A few birds, like marsh wrens and bobolinks live in areas where their feathers get damaged more often than other birds so they will go through more than one complete moult in a year.

white feather (small)Moulting is a very intense process and can be very taxing on birds. It takes a lot to of energy (and food) to grow new feathers! During this time, the birds will add more protein, calcium and iron to their diet. They also move around less because it is difficult for a bird to fly very much when it is growing new feathers. Even though moulting is tough for birds, growing a new set of feathers is really important. After all, feathers are vital for regulating body temperature, protection and camouflage, attracting a mate and, of course, flying!

You can help protect songbirds when you sign up for a Bring Back the Wild project to protect barn swallows.

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References:
http://www.vcahospitals.com/main/pet-health-information/article/animal-health/molting-in-birds/966
http://www.birds.cornell.edu/allaboutbirds/studying/feathers/molting/document_view

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