When imprinting goes terribly wrong

The dangers of intact mature male animals is a story that needs to be repeated, says Joe Stookey, a researcher and animal behaviour scientist at the University of Saskatchewan.

“Too many people are being injured or killed,” he said.

“And while the story is often about mature dairy bulls, people who don’t know any better are adopting male deer, elk or bison as ‘pets,’ and when they get older, someone is getting hurt by them, or worse.”

A simple internet search brings up dozens of stories and videos of friendly and unusual pets frolicking and roughhousing with their human handlers.

“These animals seem like a novelty, a funny or comical thing, but I know exactly what’s going on. Especially if they are males,” said Stookey, who is also a cattle producer.

Too often, the stories go on to tell of how one day things turned, and these pets or bulls, seemingly out of the blue, injured or killed someone. Dairy bulls are too often involved, but so are sheep, goats, colts and even deer.

When these incidents happen, Stookey said people automatically assume the animals were treated poorly and attacked for revenge or payback, or that the handlers were too aggressive and struck the animals.

“It really has nothing to do with how they were treated; it has everything to do with imprinting and sexual maturity,” Stookey said.

The connecting factor between all these cases is those involved are orphaned and individually raised intact males, likely bottle fed by people.

Stookey said animals are either precocial, which means they are able to get up and move around quickly after birth, such as calves, lambs, colts and chicks, or altricial, which means they are helpless at birth, such as rabbits, kittens and mice.

“For the precocial animal, it’s part of their survival to know and stick with their mother. They have around 20 to 30 hours after birth when there is a window of open time when they don’t know what or who their mother is. Usually, they recognize the first moving object they see in their environment. It’s part of a process called imprinting.”

Stookey said these hours are critical for precocial mammals. Imprinting helps the vulnerable animals survive, mapping out who they are, plus who they’ll be attracted to when they reach maturity, specifically in males.

Normally, when nature takes its prescribed course, the first object the newborn calves see and interact with is the dam or mother.

“They are all connected—milk, mother and movement. All coming from the mother. It’s built in like a blank slate, usually for the first two days. If they’re bottle raised with humans as the surrogates, the window is filled with people as their species of choice.”

Stookey said it doesn’t matter if the object is a human or even of the same species. Studies have shown when male lambs raised by nanny goats reach sexual maturity, they want to mate with goats.

Work has also been done with whooping cranes, falcons and condors using cut-out puppets of their own kind, ensuring humans stay out of sight. When released into the wild, they recognize their own because of the puppets and will reproduce. If allowed to imprint on people, they’re not interested in their own species.

“Imprinting does some really crazy things. It doesn’t even require a reward.”

He related how earlier research by notable animal behaviour expert Konrad Lorenz showed baby chicks latching onto roller skates after hatching, following them whenever they moved.

“For male dairy calves, even if they’re in their pens and get a bottle brought to them and hung on the gate every day, they’re still only seeing people. And here’s the key — when they’re individually penned, they will imprint on those people, and the more they’re handled, the worse the situation becomes.”

Because this process gives males a sense of who they are and what they’re attracted to, if the object is a person, when they reach maturity, they will engage in sexually competitive behaviour. Pushing, mounting, shoving and fighting—anything to dominate whoever they see as competition.

“If these are larger animals, we’re at their mercy. What we think is aggressive is really sexual rivalry for them, and they’ll direct it at any human. It doesn’t have to be someone they know or the person they first saw. It can be a man, woman or stranger. If it’s a human, they will compete with them.”

Stookey recounted stories of deer mounting vehicles to reach a person inside, and of people barely escaping a suddenly frenzied animal trying to engage them. There are similar reports of those not so lucky.

He said when people raise wild animals as pets, they’re setting themselves up for disaster when they mature as an intact male.

“With young bulls, they will become aggressive like they would with other bulls. It’s an extremely dangerous situation.”

Stookey said it’s not only dairy bulls affected in cattle. A research study done by Ed Price, animal behaviour expert at the University of California, experimented with Hereford bull calves, raising some individually by bottle feeding and others in groups.

Researchers found that when they reached sexual maturity, the individually raised bottle-fed animals became extremely aggressive around people,while those reared in groups didn’t display the tendency. They concluded that while bottle feeding was a consideration, being raised individually was doubly key to their behaviour.

Stookey believes the critical message is that intact male bull calves or wild animals should never be bottle fed and raised individually. If calves are identified and destined to become breeding bulls, group them with other calves starting at a young age. An even better option is a surrogate or nurse cow to raise an extra calf or two.

“If they aren’t going to be a breeding bull, castrate them. The bright spot here is there aren’t as many breeding dairy bulls being raised this way as artificial insemination has become more widely used with milking cows.”

He said most people working in the dairy industry know their bulls are dangerous and have learned how to handle them, but many may not understand why they behave the way they do.

“It’s not genetics,” Stookey said.

“It’s not all breeds of dairy bulls are dangerous. It’s that 99 percent of dairy bulls have imprinted on people by being raised alone with a bottle. We can take steps not to raise them that way. This story needs to be re-told because these injuries and deaths don’t have to happen.”

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