A story that started off as viral catnip highlighting the thoughtlessness of tourists took a dark turn on Monday.

The National Park Service announced that a bison calf, which was put in the back of a van by tourists at Yellowstone National Park who thought it looked cold, had to be euthanized.

The story of the tourists went viral over the weekend after a picture of the baby bison in the van was posted online.

East Idaho News reported:

"[Karen Richardson of Victor, who posted the picture,] says on Monday, as students were being taught at Lamar Buffalo Ranch, a father and son pulled up at the ranger station with a bison calf in their SUV." 'They were demanding to speak with a ranger,' Richardson tells EastIdahoNews.com. 'They were seriously worried that the calf was freezing and dying.'"Rob Heusevelet, a father of a student, told the men to remove the bison from their car and warned they could be in trouble for having the animal." 'They didn't care,' Heusevelet says. 'They sincerely thought they were doing a service and helping that calf by trying to save it from the cold.' "

The tourists were ticketed, but today the Park Service said that following the incident, the baby bison was rejected by its family.

"Interference by people can cause mothers to reject their offspring," the Park Service wrote in a statement. "In this case, park rangers tried repeatedly to reunite the newborn bison calf with the herd. These efforts failed. The bison calf was later euthanized because it was abandoned and causing a dangerous situation by continually approaching people and cars along the roadway."

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