By Susan Thurn,
Cable Natural History Museum
It is not an action we see in the natural world very often. It happens in tremendous numbers every spring, yet we humans rarely get a glimpse at it. Sometimes it is a simple plop, plop, plop, as the fledgling wood ducks drop from their wood cavity or wood duck house into the water or a swoop as a bird leaves its nest. The process of birds leaving their nest is so common, yet not often seen. Why is that?
Many bird nests are very difficult to find, hidden nicely among the camouflaged plants. Young fledglings are also expert ventriloquists, something that helps them evade predators. Their sounds are usually short notes that become faster whenever an adult brings food.
A baby bird is sometimes called a fledgling, the stage in which the young bird’s life has wing muscles and feathers that are developed enough for flight. It is also considered the time when parents of a chick raise it to a fully grown state. Sometimes the birds have begun flying, but are still dependent upon care and feeding from their parents. Other times birds are “fledged” once they leave the nest, even if they still haven’t flown.
Contrary to what we might think, songbirds don't "learn" to fly, and their parents don't "teach" them. Young birds have innate abilities to fly as their bodies mature gradually. When they are physically ready for flight they will fly.
It is common during June for humans to see immature birds sitting on the ground or hopping around without sign of their parents. This is a normal occurrence, as the parents are probably either hiding, watching quietly nearby or are not far away collecting food.
How can we know when we see fledglings? They are usually clumsier and less active than adults, and may have lingering tufts of down feathers and a shorter tail. They will sometimes sit in place, fluttering their wings and gaping their beaks when adults bring food. Most songbirds have a brightly-colored inner beak to help parents find their mouths, but this feature is lost as they age. As they mature, many fledglings will follow their parents, begging constantly for food.
Young of open-nesting songbirds often leave their nests within fourteen days. However, the cavity-nesting tree swallow stays in its nest longer, up to 19 days if the weather conditions and food availability are good. More young in the nest also can take longer for them to mature. With tree swallows, only 85% of their feathers are fully grown when they fledge and attempt to fly.
Pigeons stay in their nests until they are almost adults. The nests are also well-hidden, so are difficult to find, as is true of so many birds. Pigeons sometimes become even bigger than their parents as they feed and get ready to be out of the nest on their own.
Robin nestlings are fed at first by regurgitated food, then larvae or whole earthworms. After they fledge and leave the nest, the young are fed by the male for at least two more weeks. This assistance from the male allows the female to begin another clutch of eggs.
There are many more interesting stories about birds and their parental care of young. Birders are beginning to gain more interest in observing the fledgling process, recording the young birds’ calls and learning identification techniques. If you have your own stories to share about observations of birds fledging in your own back yard, be sure to share it at the Nature Watch blogspot address listed below.
For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, The Joy of Birds: Feathers in Focus opens in May, 2011. Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Also discover us on the web at www.cablemuseum.org, on Facebook, or at our blogspot, http://cablemuseumnaturewatch.blogspot.com/ to learn more about our exhibits and programs.