Imprinting in animals is most thoroughly studied in birds, although it is believed to be especially important in the hoofed mammals , which tend to congregate in large herds in which a young animal could easily be separated from its mother.
Imprinting also occurs in humans to at least some extent. An infant separated from its mother for a prolonged period during its first year may develop serious mental retardation. Irreparable damage and even death may result from a separation of several months. Birds who are human-imprinted are deemed unsuitable for release back into the wild due to these inappropriate interactions. When humans must care for orphaned or injured baby birds, Wildlife Center staffs take special precautions to prevent them from inappropriately imprinting on humans.
Human contact is kept to a minimum; the rehabilitation staff only handle birds during the feeding and cleaning process. The rehabilitation staff, students, and volunteers do not talk to the patients. For songbirds, we try to keep babies together in groups of the same species, and this is typically enough to prevent them from imprinting on humans. With our young raptors, placing them with a surrogate parent provides them with the best chance of imprinting on the appropriate species.
Surrogates provide an adult role model to young members of their species to counter their interaction with human caregivers. The surrogate parent demonstrates proper behaviors for their species and reinforces their wariness of humans. This enables the young birds to be released back into the wild with appropriate behaviors, vocalizations, and reactions to humans.
The level of interaction between surrogate and baby differs in each situation. Other surrogates show no maternal or paternal instinct, but their presence ensures that the babies can visually imprint on the appropriate species.
Because noisy flight would inhibit his ability to survive independently, he cannot be released back into the wild. Papa lives in the patient area of the Wildlife Center, and is not on display for tour groups or open houses. They are attracted to movement, sound and smell. Joe used all three of these to reinforce the poults attachment to him as their mother. When the poults hatched, he was positioned to be the first thing they would see.
The new hatchling made his way over to Joe and huddled up against his face. Over the next few hours this was repeated with all the baby birds. They came to associate the sight, sound and smell of him as their mother. But the biological imperative that drives imprinting can have its negative side. As a result, researcher Wladyslaw Sluckin proposed using the term sensitive period rather than critical period. What's more, other experiments suggested that imprinting could be reversed by gradually introducing a bird back to its own species.
Research has revealed that sexual imprinting is also possible in altricial birds those that are more helpless at birth. Experiments during the s and s revealed that a bird can show sexual preference for its own species without having any experience with another of its own species. Researcher Patrick Bateson wanted to reconcile the ideas that sexual preference is partly genetically determined but also capable of being influenced by experience via imprinting.
His experiments suggested that birds prefer sexual mates that are within their own species but don't prefer those of the opposite sex to which they were exposed early in life [source: Bateson ]. So, he theorized that the purpose was to balance inbreeding and outbreeding.
Birds are genetically predisposed to mate with their own species but also must rely on experience to ensure they don't mate within their immediate family. Sexual imprinting has also been grouped with other methods of how animals learn socialization under the more general term of species imprinting. Although Konrad Lorenz would later disavow Nazi sympathies or wrongdoing during the war, it is now believed that he played an active role in the Nazis' eugenics practices.
As a psychologist in an SS unit, he would judge individuals to be Polish-German "hybrids" and therefore unfit to breed. According to some, his beliefs in racial purity influenced his interpretations of scientific data and shaped some of his theories [source: Klopfer ]. Strictly speaking, imprinting is a phenomenon exclusive to certain bird species, just as Lorenz meant it when he coined the term.
But as we've seen, subsequent research has revealed imprinting to be more flexible than Lorenz originally thought. This calls into question the phenomenon's rigid definition. Furthermore, researchers have borrowed the term in studying how early experience can affect behavior in other types of animals.
One of the most fascinating studies involved cross fostering sheep and goats. During the s, researcher Keith Kendrick and his colleagues switched sheep and goats at birth. The animals were allowed social contact with their own species while being raised by their adoptive species. It turned out that the adopted animals preferred to mate with the species of their adoptive mother [source: Price ]. Interestingly, however, the male animals were more affected by this social imprinting than the female animals.
Males were more likely to prefer to socialize and mate with their adoptive species, and researchers found it was harder to reverse their imprinting. After the first year of being raised by a different species, the adopted animals were reunited with their own species and removed from contact with the other species. Once a year, the researchers would allow the adopted animals contact with their adoptive species to assess their preference.
Females could reverse their sexual preference back to their own species in one or two years, whereas males' sexual preferences still hadn't changed after three years [source: Goodenough et al. Other landmark studies have explored the effects of mother-infant bonding among mammals.
Famously, researcher Harry Harlow discovered rhesus monkeys preferred surrogate model mothers wearing terrycloth as opposed to surrogate model mothers made of wire but providing food.
It's believed that giant pandas won't prefer to mate with each other if handled by humans from a young age. As a result, some zookeepers dress in panda suits. Erroneous imprinting on humans can obviously have adverse effects on individual animals and their ability to survive in the wild.
Birds that imprint on humans struggle to learn survival skills or to assimilate back to their own species.
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