At Yellowstone National Park, a bison calf was loaded into a vehicle by tourists , while being concerned for its welfare. The bison calf could not be reunited with its herd and had to be euthanised.

On Monday, park officials said while reasserting the importance of avoiding wildlife.

Along with this tourist incident last week, several other recent cases have also taken place. They have led to fresh warnings.

According to the park rules, the visitors are required to stay at least 25 yards (23 metres) away from all wildlife. In case of bears and wolves they must be 100 yards away.

Visitors showed up with the newborn calf to a park facility on May 9. Officials called this a dangerous move because adult bison are too protective of their young and will attack to defend.

According to The Australian, rangers took the animal back to where it was picked up from. However, after several tries they failed to get it back with the herd.

In a statement given by the park, they said that the bison calf was later euthanised because it was abandoned. Moreover, a dangerous situation was caused by continually approaching people and cars along the roadway.

The visitors who loaded the bison calf were called for touching park wildlife. They were fined $150, says Yellowstone National Park spokeswoman Charissa Reid said.

She refused to the name of visitors or issue a copy of the citation amid the investigation, says CNN.

In a recent high-profile case, a video recording showing a woman trying to pet an adult bison as it rested on the boardwalk around Old Faithful.

There was another incident where tourists posed for photos while they were impossibly and dangerously close to a bison. This had resulted in a traffic jam on a road.

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It was last year, when five visitors were seriously injured after approaching the massive animals from very close distance.

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Important guidelines and rules have been published on the Yellowstone National Park website.