Yellowstone National Park authorities are asking for the public's help after a man intentionally disturbed a newborn bison calf in an "unfortunate" incident that resulted in the animal's death. 

The incident occurred on the evening of May 20 in the park's northeastern corner in Wyoming.

The National Park Service described the man as White and in his 40s or 50s, and wearing a blue shirt and black pants. 

He approached the bison in Lamar Valley near the convergence of the Lamar River and Soda Butte Creek. 

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The calf had been separated from its mother when a herd of bison crossed the Lamar River. 

The man pushed the baby bison up from the river and onto the roadway, and visitors later observed the calf walking up to cars and following people. 

"Interference by people can cause wildlife to reject their offspring. In this case, park rangers tried repeatedly to reunite the calf with the herd. These efforts failed," the Park Service explained. 

The calf was later killed by Yellowstone staff because it was abandoned by the herd and caused a hazardous situation by approaching cars and people along the roadway.

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The agency wrote that approaching wild animals can drastically impact their well-being and, as in this case, their survival. 

Park rules require that individuals stay at least 24 yards away from all wildlife and at least 100 yards away from bears and wolves. 

Disregarding such regulations can lead to fines – or even injury or death.

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

People with any information that could help the investigation are being asked to contact the Yellowstone National Park tip line at 307-344-2132 or to email YELL_Tip@nps.gov.