You may have seen them over the last months busily carrying load after load of insects to feed their ravenous nestlings, then being raucously pursued by fledglings demanding yet more food sometimes with two or even three batches of babies through the season. All this effort has taken a toll on the adult birds feathers and now, despite the daily care they have taken preening and cleaning them, the feathers are worn out. The birds are lying low during their molt the annual or twice yearly loss and regrowth of feathers done by most songbirds. But dont expect to catch a glimpse of bald birds each worn feather becomes loosened in its socket and is pushed out by the growth of a new feather.
The process takes from 5 to 12 weeks for songbirds, after which some will appear in winter plumage quite different from the bold patterns some males sport in summer. For example, American Goldfinch males are bright canary yellow with bold black accents during the breeding season, but become a quieter butterscotch color, much like females and juveniles, in their winter garb. Similarly, you may see a male Western Tanager that has lost his gaudy orange head feathers and exchanged them to the muted gray of a female before starting the long, dangerous migration to Costa Rica for the winter.
Other groups of birds go about the molt differently. Ducks, geese and some other water birds go through a rapid synchronous molt. They change their feathers quickly in a period as short as two weeks which renders them flightless for that period. This seems like a risky business but researchers have deduced that since these birds are heavy relative to their wing surfaces, losing a few feathers at a time would seriously hamper flying ability, so they get it over with as quickly as possible and minimize the length of time that they are especially vulnerable to predators.
Raptors (eagles, hawks, falcons and their kin) make their living on the wing and cant afford to suffer periods of impaired flying abilities. These birds may take as long as two years to complete a molt. The loss of flight feathers must be symmetrical or flying would be skewed. A woman who raised an owl that could not be released into the wild observed this in action. She reported that her feathered friend pulled a loose wing feather out and gave it to her, then immediately removed the corresponding feather from the other wing.
To give young Turkey Vultures a good start, they dont molt their flight feathers until they are two years old. The vultures soaring over minus a couple feathers are almost certainly adults.
In most birds, tail feather replacement is from the center of the tail toward the outer edge. Woodpeckers reverse this for a very good reason. Watch closely the next time you see one ratcheting up a tree and you will see that it braces itself firmly using its stiff tail feathers. The key for this is an inner pair of long feathers. Those are retained until the outer tail feathers have been replaced with fresh, strong vanes, keeping the woodpecker able to fully function searching for insects in the bark.
You may find a single feather in your yard evidence that one of your birds has cast it off for a brand new set of feathers to get it through the winter or prepare it to head off to winter habitat in Mexico, Central America or South America. Enjoy the memento!
Other groups of birds go about the molt differently. Water birds such as ducks and geese undergo a swift process known as “synchronous molt.” They can undergo a feather change in as little as two weeks, which causes them to become immobile during that time. It may seem dangerous, but researchers have found that these birds are heavy in relation to their wing surfaces, so losing a few feathers at a time would significantly impair their ability to fly. As a result, they try to get rid of the feathers as soon as possible to reduce the amount of time they are particularly vulnerable to predators.
Because they “make their living” on the wing, raptorseagles, hawks, falcons, and their relativescannot afford to experience periods of reduced flying ability. For these birds, the entire molt process could take up to two years. Flying would be skewed if there was an uneven loss of flight feathers. This was witnessed in action by a woman who reared an owl that was unable to be released into the wild. She said that her feathered companion swiftly withdrew the matching feather from the other wing after pulling out a loose wing feather and giving it to her.
One of “your” birds may have abandoned a single feather in your yard in favor of a fresh set in order to survive the winter or get ready to migrate to a new home in Mexico, Central America, or South America. Enjoy the memento!.
Throughout the last few months, you may have observed them laboriously carrying an abundance of insects to feed their famished nestlings. Later, the fledglings would raucously pursue them, demanding more food. Occasionally, they would have two or even three batches of babies during the season. The adult birds’ feathers have suffered from all this work, and now they are worn out even with the daily care they give them to preen and clean. The birds are hiding while going through their molt, which is when most songbirds lose and grow new feathers once a year or twice a year. However, don’t expect to see any bald birds; instead, each feather that wears out is forced out of its socket by the growth of a new one.
The majority of birds replace their tail feathers from the middle to the outside. Woodpeckers reverse this for a very good reason. The next time you witness one ratcheting up a tree, pay close attention to how it braces itself with its stiff tail feathers. An interior pair of long feathers is crucial for this. These are kept until the woodpecker’s outer tail feathers are replaced with new, robust vanes, allowing it to continue its normal function of scrounging for insects in the bark.
“The oil that coats feathers provides waterproofing, which is important since the only thing worse than being cold is being cold and wet,” Marra says. “Birds’ feathers provide remarkable insulation against the cold.” Also, birds tend to get puffier in the winter, much like people do with their coats. According to Marra, “a bird’s body heat warms the air between its feathers.” In order to retain as much air in their feathers as possible, birds fluff up in the cold. The more trapped air, the warmer the bird. Feathers are wonderful for the parts of a bird that are covered in feathers, but what about its legs and feet? Surely, birds don’t have pockets where they could store their feathers, or do they? One way birds stay warm on their legs and feet is by standing on one leg while the other is nestled comfortably in their feathers. After that, they swap to let the other leg go. Like other members of the swan, goose, and duck families, mute swans use a unique network of veins and arteries known as a counter-current heat exchange system to keep their feet and legs warm throughout the winter. (Flickr photo by Paul Grayson).
Marra explains that birds have an incredibly effective method of keeping their legs warm: “They have a counter-current heat exchange system in their legs: veins and arteries in the leg are close to each other, and as warm blood leaves the body, it heats up the cold blood returning to the body.” Have you ever wondered why the legs of ducks and geese don’t freeze in the icy waters of winter? It’s amazing how many different bird species congregate in the winter to search for difficult-to-find food and keep a close eye out for predators. Additionally, some birds gather at night in a ball to ward off the chill of winter. According to Marra, “many small birds, like house wrens, Eastern bluebirds, and black-capped chickadees, will gather in large groups at night and crowd together in a small, tight space to share body heat.” They can roost closely together in dense shrubbery or trees. Additionally, people frequently congregate in tree cavities and abandoned birdhouses in order to preserve heat. So . Wear a warm coat, preferably made of down; always keep your extremities warm; and during the gloomier winter months, maintain social interactions. These are all tips we’ve undoubtedly heard before, but now we know where they originated.
Even after preparing yourself with a hat, coat, scarf, and gloves and watching the weather forecast, you still become cold from the wind and snow after a little while. It turns out that birdseven the small, delicate ones like chickadees and titmicearen’t so delicate after all, and they have a few tricks up their sleeves (uh, wings), too. If it’s so difficult for humans to stay warm outside, how do birdsespecially the little delicate guys like chickadees and titmicesurvive the single-digit temperatures and whipping winds of winter? Feathers are their outermost layer of protection against the cold. People adore down-filled winter coats for good reasonfeathers make excellent insulation. “The primary function of feathers is to provide warmth for numerous species,” explains Peter Marra, the director of the Smithsonian Migratory Bird Center at the National Zoo. “Feathers are highly specialized structures that serve numerous purposes.” Feathers are useful for a variety of things, such as camouflage and attracting mates. As with this blue jay, one of the most crucial tasks performed by feathers in the winter is to keep the bird warm and dry. (Flickr photo by Nick Harris).