Wild Birds Unlimited Product & Hobby Education Manager Brian Cunningham explains how food helps birds change their appearance through the seasons.

One of the defining features of a bird is its plumage, or the layer of feathers that cover a bird and the pattern, color and arrangement of those feathers. Similar to how people make seasonal wardrobe changes, many birds make a transformation of their own, losing and replacing feathers through a process known as molting. 

“Typically, birds molt feathers in regular patterns or on specific parts of their bodies, and it may take weeks or months for birds to complete the molting cycle,” said Brian Cunningham, Product & Hobby Education Manager for Wild Birds Unlimited. “When a bird replaces all of the feathers on its body, it is described as a full molt. A partial molt may occur between full molts for some species of birds as they replace only a portion of their feathers; perhaps just replacing head, wing or tail feathers.”

An example of a partial molt is when American Goldfinches transform into their bright breeding plumage by replacing only their body feathers in the spring. Otherwise, they replace all their feathers, including body feathers, during a full molt each fall. Most backyard feeder birds molt from July to September. Some molt through October like Downy Woodpeckers, Mourning Doves and Eastern Bluebirds. American and Lesser Goldfinches can be seen molting through December.

It takes the right building blocks to grow feathers. Protein is essential for growing strong feathers, and fats are essential for feather coloration.

“Every molting bird needs extra proteins to grow strong feathers for proper flight and effective insulation,” said Cunningham. “Feathers are more than 90% protein, primarily keratins. This is similar to our hair and finger nails.” 

Birds also need extra fats for energy to grow feathers and fats help provide proper coloration to best attract a mate. Poorly colored birds are less likely to breed and dietary pigments help communicate reproductive fitness to prospective mates by providing a vibrant and bright plumage—a sign of being successful at obtaining both a sufficient quality and quantity of food. 

“Just as pigment dyes are used to color our clothes, colors in feathers come from different foods being eaten while the feathers are growing,” said Cunningham. “The more color and more brightly colored a male House Finch, for example, the greater the likelihood of attracting a mate.” 

“There are several food options for birds to meet their protein and fat cravings,” said Cunningham. “Some of the seed blends we recommend at Wild Birds Unlimited include our Spring Nesting Blend which is ideal for molting birds as well as Choice, No-Mess and Supreme. Our Nutty for Nuts and other seed cylinders are great sources of protein and fats while also being a convenient way to feed the birds. Straight seeds like, shelled peanuts, Nyjer and sunflower chips are good as well as mealworms, no-melt suet and Jim’s Birdacious Bugs & Bits.”

It’s important that birds get these vital proteins and fats otherwise feathers may be improperly colored or form defectively such as being frayed or curved. If their colors are duller, birds may have trouble attracting a mate. If the feathers are defective, it could seriously hinder their flying or insulation abilities. 

“Distinguishing birds that are molting from those that are not can sometimes be difficult,” said Cunningham. “Though some birds may look disheveled or lose patches of feathers and appear to be ‘balding,’ most birds’ feather loss and replacement are far less noticeable.”

The good news is that anyone can become an expert at identifying molting with various species of bird. Studying the habits, schedules and variations of birds will allow you to understand each species more and get a better handle on their individual molting process. 

“If you are ever curious to learn more about all the high-protein foods birds need, come visit us,” said Cunningham. “At Wild Birds Unlimited, we have everything to help birds keep going—and re-growing feathers—during this critical time.”