In humans and other higher animals it is chiefly the
limbic structures of the brain that embody the long-term memory shaped by experiences. The best-known form of imprinting is that of small children and young animals, who limit their social preferences to their conspecifics – usually their mother first – after coming into contact with them. This so called
filial imprinting is most obvious in
nidifugous birds, which follow their parents around due to imprinting with their visual appearance, sounds and other behavioural expressions. It was first reported in domestic chickens, by
Sir Thomas More in 1516 as described in his treatise
Utopia, 350years earlier than by the 19th-century amateur biologist
Douglas Spalding. It was rediscovered by the early ethologist
Oskar Heinroth, and studied extensively and popularized by his disciple
Konrad Lorenz working with
greylag geese. Lorenz demonstrated how incubator-hatched geese would imprint on the first suitable moving stimulus they saw within what he called a "
critical period" between 13 and 16 hours shortly after hatching. For example, the goslings would imprint on Lorenz himself (to be more specific, on his wading boots), and he is often depicted being followed by a gaggle of
geese who had imprinted on him. Lorenz also found that the geese could imprint on inanimate objects. In one notable experiment, they followed a box placed on a
model train in circles around the track. Because birds hatched in captivity have no mentor birds to teach them traditional migratory routes, D'Arrigo hatched chicks under the wing of his glider and they imprinted on him. Then, he taught the fledglings to fly and to hunt. The young birds followed him not only on the ground (as with Lorenz) but also in the air as he took the path of various migratory routes. He flew across the
Sahara and over the
Mediterranean Sea to
Sicily with
eagles, from
Siberia to
Iran (5,500 km) with a flock of
Siberian cranes, and over
Mount Everest with
Nepalese eagles. In 2006, he worked with a
condor in South America.
American coot mothers have the ability to recognize their chicks by imprinting on cues from the first chick that hatches. This allows mothers to distinguish their chicks from parasitic chicks. The
peregrine falcon has also been known to imprint on specific structures for their breeding grounds such as cliff sides and bridges and thus will favour that location for breeding. == Sexual imprinting ==