NEW YORK - A bison calf at Yellowstone National Park had to be euthanised after a man apparently tried to help it, causing the herd to reject it, park officials said this week.

The newborn calf began following cars and people, officials said, and was killed because it posed a hazard to visitors.

The episode began on Saturday evening, when the calf was separated from its mother as their herd crossed the Lamar River in Wyoming, in the park’s north-east corner.

When the calf struggled to reach the group, a middle-aged man “intentionally disturbed” it, pushing it from the river onto the road near the river’s confluence with Soda Butte Creek, the National Park Service said in a statement on Tuesday.

It is unclear where the herd was at that point.

“Interference by people can cause wildlife to reject their offspring,” the Park Service said.

“In this case, park rangers tried repeatedly to reunite the calf with the herd. These efforts failed.”

Law enforcement officers were trying to identify the man, who was wearing a blue shirt and black pants while interacting with the animal.

Park regulations require visitors to stay 23m away from wildlife such as bison, elk and deer and 91m away from bears and wolves.

Approaching animals can drastically affect their well-being and survival, said the Park Service.

“Disregarding these regulations can result in fines, injury and even death,” the Park Service added.

“The safety of these animals, as well as human safety, depends on everyone using good judgment and following these simple rules.”

The Park’s decision to put the calf down was met with criticism on Facebook.

While some were not pleased with Yellowstone’s decision to kill the calf, others questioned why the park was trying to track down the man who apparently helped it.

“Why are you plastering his face on the Internet and trying to track him down? You killed the animal. He did not. I’m all for education, but why punish someone for trying to help?,” one Facebook user posted.

The Park responded to these and other responses by saying “national parks are very different” from animal sanctuaries and zoos.

“We made the choice we did, not because we are lazy, uncaring, or inexpert in our understanding of bison biology,” the Park said in one of its Facebook replies, adding that it took the decision it did because “national parks preserve natural processes”.

“Every day in national parks, some animals die so that others may live. In fact, as many as 25 per cent of the bison calves born this spring will die, but those deaths will benefit other animals by feeding everything from bears and wolves to birds and insects,” the Park said.

“The calf’s behaviour on roads and around people was hazardous, so rangers had to intervene: but the calf’s body was left on the landscape,” it added.

The Park also responded to queries about why they could not have cared for the calf or sent it to a sanctuary.

It said regulations prohibit the transport of bison out of the park unless those bison “are going to meat processing or scientific research facilities”.

Some Facebook users also defended the Park’s actions, with one person saying “animals die in the wild”.

Another person said that animals leave their babies behind “all the time”, and pointed out that even if the mother had abandoned its calf, “nature would’ve taken its course without human interference”.

Yellowstone regularly has to remind visitors not to interact with park wildlife.

In 2018, a man was arrested after taunting a bison at Yellowstone National Park.

In 2016, a bison calf was euthanised after being placed in the back of a sports utility vehicle and rejected by its herd. And in 2015, a woman was injured while trying to take a selfie near a bison. NYTIMES