Reflections in Nature: Mama’s voice
Our granddaughter, Eve, is going to have a baby in early March. She and her husband are so excited about having a baby and becoming parents. For several months, Eve has been talking, reading and singing to her unborn child.
Recently, I read in a book titled “Intelligence in Animals” (Reader’s Digest) 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 to 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 the 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 insures that all of the eggs in the nest will hatch within hours, even though the eggs were 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. Typically, it takes about a day for all of the ducklings to hatch.
After emerging from the shells, the ducklings remain in the nest with their mother for about 24 hours until their down has dried. The ducklings then are ready to leave the nest and follow their mother to the nearest wetland to feed.
In an experiment, a mother duck was replaced with a decoy to try and fool the ducklings into believing that the decoy was their mother. Wherever the decoy was taken, the ducklings followed.
Eventually, those doing the experiment placed a cardboard box, which was painted with red and white stripes, containing a loud speaker 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.
One experiment was done in which a deaf female turkey laid 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 were incubated in silence.
After hatching, the chicks that heard their mother’s call pecked 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. Therefore, when the 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, which only responds to its mother’s call, has learned to associate her call with food.
Doctors now know that expectant mothers also can communicate with their unborn babies. It has been learned that a baby starts feeling its mother’s touch at about 20 weeks. It is even said that babies recognize the difference between their mother’s touch and pats of others.
Bower retired after 34 years as a wildlife conservation officer for the state Game Commission. Questions and comments may be sent to him at 1224 Redington Ave., Troy PA 16947.