As August progresses, we hear fewer and fewer birds singing. In that way it is a sad time, as we realize summer is on the wane. The loudest sound outdoors these days is coming from the cicadas, especially on windless, hot days. It is then that their buzzing sound seems to be amplified. It is a sound I associate with the last weeks of summer.
You may think that many of the birds have already turned to the south and while that is true for some species, especially the shorebirds, most other species are still around but not as visible as they were in June and July. They are done nesting and so there is no need to sing their courtship songs or songs to defend their territories. But there is another reason why they have gone silent and that is because of the process known as molt.
After their young have fledged, songbirds in the Eastern half of the U.S. start to lose and replace both body and flight feathers. This replacement happens in a systematic way and all birds go through it once a year. It is necessary to replace feathers that have worn out by the frenetic activity of the breeding season and bleaching by the sun. Without this critical part of their anatomy in tip top shape, their very survival is at stake.
When the birds are growing new flight feathers on their wings, they are especially vulnerable. There may be gaps too and this makes flight more difficult. So in order to not attract attention at this critical time, birds like the robin, warblers, sparrows and thrushes are staying low in the vegetation and keeping a code of silence. Flying under the radar you might say.
While songbirds lose feathers sequentially, waterfowl, loons and grebes, lose all their flight feathers at once. This mean they are unable to fly for a month, putting them in a more vulnerable position then the songbirds. It is during this stage of their life cycle that they begin to look scruffy. If you have been continuing to provide bird seed all summer, in August you might notice that the birds have lost the sleek, smooth look of spring. You might see some that are still missing feathers. Putting wild bird food out (if you don’t have bear or raccoon problems) helps the birds to reduce their search for food, saving energy for the production of new feathers.
As for the young birds just out of the nest, molt happens just on the body feathers. Their flight feathers are sturdy enough and they need to save their energy for the upcoming migration. Most of these new arrivals will not get their adult plumage until next year.
There is also such a thing as a partial molt which usually occurs in the spring as the adults prepare to begin another
reproductive season. One good example is the Common Loon. When it leaves the northern lakes it doesn’t look anything like the bird that arrived in the spring. Its feathers are a drab brown and grey. But come spring, while still in the Gulf of Mexico, the adults molt again and become the stunning black and white birds that millions of people look for each summer.
Like the birds, you might say that those of us who live in the northern states molt at the end of summer. We reluctantly put away the swimming suits and shorts and replace them with cold weather attire. Some of us will even migrate south for the winter, while the rest of us watch and enjoy the seasons and the landscape change again.
By Kate Crowley