Mother hens dictate diet
Ptarmigans teach their
brood healthy eating habits.
18 July 2001
The maternal command to eat your greens now has a feathered equivalent.
Female ptarmigans steer their chicks away from junk food towards a
Teaching such as this is known for only a few species, including
chimpanzees and cheetahs, says Jennifer Clarke of the University of
Northern Colorado, Greeley. "To find it in a little chicken-like bird
very surprising," she says.
Mother ptarmigans peck off a piece of plant food and drop it in front
their chicks, Clarke told the meeting of the Animal Behavior Society
Corvallis, Oregon. They then point at the titbit and the plant from
it came with their bill and make a special food call.
Studying willow ptarmigan (Lagopus lagopus) in California's Sierra
mountains, Clarke and her colleagues found that mother birds teach their
chicks to eat six different plant species, although youngsters will
many more of their own accord.
Mothers make a particular effort to get their brood to eat dwarf alpine
willow. Nutrient analysis revealed that this plant is a particularly
source of protein.
Educated chicks' food preferences persist into adulthood and may influence
what they teach their own offspring. Different areas might have different
food cultures, depending on what plants are available and the tastes
individual birds. Clarke aims to test this idea by studying ptarmigans
living in the Rocky Mountains.
The necessity for young birds to learn quickly which of the many plants
around them they should eat may have driven the evolution of active
teaching, says Jennifer Basil, who studies animal learning at Brooklyn
College, New York. "It's a situation where learning the information
own just isn't going to be fast enough," she says.
Basil believes that we have underestimated the sophistication of the
interactions and communicative powers of animals. More examples will
to light the harder we look, right across the animal kingdom. "We tend
think that only warm and furry animals can do it, but that's not the
works," she says.
If we could understand how animals instruct one another, Basil adds,
might be able to teach machines the same trick. One goal is to build
of robots that can cooperate and function independently of humans -
they could teach one another, that would be pretty useful for exploring
surface of Mars, for example," Basil points out.
Ĺ Nature News Service / Macmillan Magazines Ltd 2001