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Molt, woodpeckers, and orioles
Answers to readers' questions about the timing of molt, woodpeckers at hummingbird feeders, and orioles' feeding habits
Contributed by Julie Craves
Published: December 22, 2010
What determines when a bird molts? And do all birds of the same species molt at the same time? — Chris Meldrum, Farmington Hills, Michigan
Feathers are remarkable structures, distinguishing birds from all other animals. Colors and patterns can signal species, gender, age, or dominance; feathers facilitate flight; and they act as insulation and protection. Feathers are exposed to many damaging things, including sunlight, soil, bacteria, and vegetation. It is essential for them to be in good shape, so all birds replace all or most of their feathers at least once a year.
Molting is triggered by changes in hormones, which in turn are affected by seasonal changes such as day length. Because growing new feathers requires a lot of metabolic energy, regular molts usually occur outside of other stressful life events like migration or breeding.
When birds go through a complete molt — replacing all of their feathers — they do not lose and regrow all feathers simultaneously. Wing and tail feathers are typically molted systematically. In songbirds, it’s common for the primary flight feathers (the nine or ten outermost wing feathers) to be shed and replaced from the middle of the wing to the tip. At the same time, the three wing feathers closest to the body are replaced. Then the rest of the secondary flight feathers are molted, starting in the middle of the wing and progressing toward the body. Tail feathers are often shed and replaced in pairs from the middle of the tail outward. While the tail and wing feathers are molting, body feathers are also being replaced. The process usually doesn’t result in bare spots, but some cardinals and jays do become bald on their heads for a few weeks.
For most small songbirds, a complete molt occurs in fall and takes about one or two months, and a bit longer for resident birds that don’t need to migrate. Within each species, the timing varies from bird to bird. Sometimes males start molting sooner than females, or birds that have late broods may molt later.
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Woodpeckers visit my hummingbird feeder almost every year. Is this unusual? — Thomas Swainson, Portland, Oregon
Quite a few species of birds — as well as insects, bats, flying squirrels, and other animals — will make use of hummingbird feeders. Sometimes the birds are just looking for a quick drink of water and can obtain it from rainwater collected in feeder nooks or the well of an ant guard.
A few bird species, however, are nearly as fond of nectar as hummingbirds. Orioles frequently visit hummingbird feeders or similar feeders made just for them. As you’ve noted, woodpeckers also take advantage of hummingbird feeders. Gila, Red-bellied, Acorn, and Downy Woodpeckers are among the North American species known to drink sugar water from feeders.
While many woodpeckers primarily eat insects, some species — notably sapsuckers — utilize tree sap that they obtain from wells carved on trunks and branches. Curiously, I haven’t heard of sapsuckers using hummingbird feeders, but hummingbird use of sapsucker wells is thoroughly documented.
In arid regions, woodpeckers may drain a hummingbird feeder just for the fluids, even if they don’t regularly drink nectar. Therefore, it is important to mix your sugar water at the ratio of four parts water to one part sugar so that it’s not too concentrated. (This approximates the level of sugar in natural nectar.) And remember to clean and refill your feeders with fresh solution often so that it doesn’t ferment and become harmful to birds. |
Baltimore Orioles use our feeders in spring, but once they build their nests, they disappear until the end of August. Why don’t they use the feeders in summer or bring their young to the feeders in the fall? — David Miller, Bremen, Indiana
During spring migration, orioles often feed on nectar, either from trees that bloom in spring or from sugar-water feeders, fresh fruit, or fruit jelly put out at feeding stations. Once nesting begins, orioles and most other songbirds require a highly nutrient-dense diet comprised mostly of insects to feed their young as well as to sustain themselves during this busy, energetically demanding time.
In the fall, they need foods that allow them to fatten up for their long migratory journey to the tropics. In addition to insects, the fall diet can include fruits, especially fruits that are high in fats, such as dogwood berries. Feeder offerings are probably not as appealing to them as they prepare to migrate.
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