Some of our feathered friends have already laid their eggs and are now in the process of incubating these eggs. The length of this incubation period varies, depending on the species.

For example, the incubation period for most songbirds will be approximately two weeks, while the incubation period for ground nesters will be approximately one month.

I read an article entitled “Intelligence in Animals” in a Reader’s Digest magazine that it is very important for young wildlife to be able to identify the sound of their parents’ calls, especially their mothers.

Animal mothers have a common bond with human mothers in that they tend to bear the brunt of raising their young. In fact, the education of their offspring can begin even before the actual birth.

While a female mallard is incubating her clutch of eggs, she talks to her unhatched offspring and they talk back. This conversation begins about 17-19 days after her eggs have been laid and when an embryo duckling’s head pushes into the air space at one end of the egg. This teaches the youngsters the call of their own species and more importantly the sound of their mother’s voice.

As soon as the eggs hatch the young ducklings know their mother’s call. This is very important because the ducklings are on the move with their mother within 24 hours. At this point, the sound of their mother’s voice is more important than her appearance.

The ducklings need to find mom immediately or lose their lives to a predator.

Shortly before hatching, the nearly developed embryos inside the egg produce clicking and peeping sounds known as pipping. These vocalizations help synchronize hatching among different members of the brood. It also ensures that all the eggs in the nest will hatch within hours, even though the eggs are laid days apart.

The female responds by making soft clucking sounds to her unhatched ducklings. These early communications are a crucial part of a process known as imprinting, in which the ducklings learn to recognize their mother’s voice. This ensures that the brood will follow their mother when it’s time to leave the nest.

As the hatching process begins each duckling penetrates the inner shell membrane of the air cell with its bill, causing its lungs to start functioning. Next, the duckling takes on the arduous task of breaking out of its shell. The young waterfowl uses an egg tooth, which is a hard horny structure on the upper tip of the bill, to break through the outer shell.

Usually, it takes approximately one day for all the ducklings to hatch. After emerging from the shells, the ducklings remain in the nest with their mother for 24 hours until their down has dried. The ducklings are now ready to leave the nest and follow their mother to the nearest wetland to feed.

In one experiment, a mother duck was replaced with a decoy to fool the ducklings that the decoy was their mother. Wherever the decoy was taken the ducklings followed. Eventually, those doing the experiment placed a cardboard box (painted with red and white stripes) containing a loudspeaker with a recording of the mother’s call being played. The ducklings immediately left the decoy and gathered near the box, proving that sound was more important than visual to the young ducklings.

Another experiment was done with a deaf female turkey that had laid her eggs, sat on the nest and incubated the eggs in the normal way. However, after the chicks hatched and began to run about, the mother hen was unable to recognize her chicks and tried to kill them. This proved that she needed to hear the contact call to suppress her aggression.

A test was done on a colony of ring-billed gulls, with one clutch of eggs exposed to the sound of the mother’s maternal feeding call, while the other clutch of eggs was incubated in silence.

After hatching, the chicks that heard their mother’s call began pecking at her beak, which encouraged her to regurgitate food for the chicks. The chicks that were incubated in silence did not peck at their mother’s beak and received no food.

Gulls live in colonies. A wandering chick is most likely to be attacked by other gulls. If a female gull realizes a chick is missing from the nest she frantically calls to the wandering chick, who responds to her call. When the female hears her youngster’s call she lets out a special mewing call, and the hungry youngster runs back to the nest. The chick, who only responds to its mother’s call, has learned to associate her call with food.

Doctors now know that expectant mothers can also communicate with their unborn babies. It has been learned that a baby starts feeling its mother’s touch at approximately 20 weeks. Most pregnant mothers are aware that the baby responds to music.

It is even said that babies recognize the difference between their mother’s touch and pats of others. These are ways that the mother can connect with the baby while in the womb.

I have often seen a pregnant woman rubbing or patting her stomach and always thought this was done because of pain. Now, I realize she was talking to her unborn child. Through the years, I have heard that many pregnant women talk, read and sing to their unborn children.

Bill Bower is a retired Pennsylvania Game Commission Wildlife Officer. Read his blog and listen to his podcasts on the outdoors at www.onemaningreen.com.