by Whitney Bell
Recently, a special love story garnered an enormous amount of publicity. A lot of proposals and wedding dance videos go viral, so what’s the big deal about this one? It has to do with a “Crowe” and a crane. Specifically, the Smithsonian Conservation Biology Institute (SCBI) zookeeper, Chris Crowe, and a white-naped crane, Walnut, who imprinted on humans and chose Chris as her life partner.
The white-naped crane, scientific name Grus vipio, is a species of large bird that is native to Mongolia, southern Siberia, Korea, Japan and central China. These birds are listed as a “vulnerable” species, which means they are not yet endangered, but should be protected and monitored to prevent them from becoming extinct in the near future. To ensure genetic diversity in the population and to maintain species numbers, white-naped cranes are bred at SCBI.
One of our main characters, Walnut, was born and raised in captivity and actually imprinted on humans rather than her own species. While we can’t confirm the allegations, it’s rumored that Walnut killed two potential mates that biologists attempted to pair her with. Walnut would, however, perform a mating dance for her human zookeeper, ironically named Chris Crowe. Chris has bonded with Walnut, gained her trust, and is able to artificially fertilize Walnut with genetic material from male cranes that are part of the species survival plan. With this method, Walnut has laid 8 eggs. Shortly after being laid, the eggs were collected and given to a surrogate, or stand-in, crane couple for fear that Walnut would not recognize her chicks as members of her species nor take care of them because she imprinted on humans. This would also explain why Walnut might be aggressive (and murderous) towards the male cranes biologists originally attempted to pair her with.
So what is imprinting and why do birds do it? Imprinting represents a critical developmental time in an animal’s life when it gains its sense of species identity. This is a rapid and crucial learning process during which a newborn animal learns its identity, establishes patterns of behavior, recognition, and attraction to other members of its species. The species they imprint on will be the species that they associate themselves with for life. Since Walnut was born in captivity and raised by humans, Walnut imprinted on humans and considers herself a member of the human species. She would not recognize other cranes as members of her species. This explains why she would not mate with a male white-naped crane, performed a mating dance towards Crowe, and why zookeepers were concerned about letting her keep and hatch her eggs.
Wildlife conservationists who raise or rehabilitate young birds will tell you how important it is to prevent a baby bird from imprinting on humans. Once a bird has imprinted on humans, it isn’t considered eligible to be released back into the wild because they frequently display inappropriate behaviors and have trouble communicating with the actual members of their species and thus may not survive. Conservationist staff take strict precautions to ensure that their birds do not imprint on humans. Specifically, human contact is kept to a minimum, workers don’t talk to the birds, and bird handling and interaction is only done when necessary such as during feeding times. Some workers wear face masks to disguise themselves or feed the baby birds using a hand puppet that looks like a member of the birds’ own species!
We’ve heard of stories and seen adorable videos of baby animals accepting another animal as their mother, but for the reasons mentioned above, surrogacy of wild animals by another species, especially those planning to be returned to their habitats, should be avoided.
