A rare white bison calf Native American communities have been celebrating since its birth in Yellowstone National Park has not been seen since June, according to the National Park Service.

The white bison calf was born on June 4 in Lamar Valley, captured on camera by visitors and photographers. The calf’s photos were shared online, gaining the affections of social media users and Native American tribes who view the animal as sacred.

“To date, park staff have been unable to locate the calf,” the National Park Service announced on its website Friday. “To our knowledge, there have been no confirmed sightings by park visitors since June 4.”

According to the park service, the calf is leucistic and not albino. Leucistic animals like the calf have black eyes and hooves with some pigmentation, the park service wrote. 

Calling the calf’s birth a “rare natural phenomenon,” the park service said a similar birth happened once in the late 19th century, before bison were nearly extinct. The birth is believed to happen in 1 in 1 million births, and perhaps even less frequently than that.

The birth of the calf in June may be due to a “natural genetic legacy” present in Yellowstone’s bison. The wild bison population in Yellowstone has slowly been rebuilt, the park service said. 

The bison population typically ranges from 3,000 to 6,000 animals in two subpopulations. The northern herd breeds can be found in Lamar Valley and on high plateaus surrounding it, while the central herd breeds in Hayden Valley, the park service said.

According to the park service, each spring, about 1 in 5 bison calves die after birth due to “natural hazards.”

White bison is sacred to Native American tribes

According to the National Park Service, Native American people have passed down a tale about the white buffalo calf for generations.

There was a famine that prompted the Lakota chief to send scouts to hunt for food. The scouts saw a figure and approached it, finding that the figure belonged to a woman. One of the scouts, fueled by sexual desire, went to approach the woman despite the second scout telling him she was sacred. 

A cloud surrounded the man and the woman, then he turned into a pile of bones, the park service said. When the second man walked up to the woman, she told him she was wakan, or holy. She told him to go back to his people and tell them she had arrived.

When she arrived, she brought the white buffalo calf chanupa, or pipe, which is “the most sacred object a person can possess,” the park service said. She also taught the tribal members the seven sacred ways they could pray. She then told the people she would come again and bring back harmony and spirituality to a world in desperate need of it. 

The holy woman rolled around the earth four times, changing colors until she turned into a white buffalo calf and disappeared. Once she left, herds of buffalo came to surround the people. 

Now, Native American people believe that when a white buffalo calf is born, their prayers are heard and that the prophecy will be fulfilled.

“To American Indians, a white buffalo calf is the most sacred living thing on earth,” the park service wrote on its website. “Some American Indians say the birth of a white calf is an omen because the birth takes place in the most unexpected places and often happens among the poorest of people.”

See photos:Photographer shares 'magical' photos of rare white bison calf at Yellowstone

Calf named, welcomed at ceremony last week

Shortly after the white bison calf was born in June in Yellowstone National Park, Native American community members shared their enthusiasm and also welcomed the animal in a ceremony on Wednesday.

Chief Arvol Looking Horse spoke at the ceremony and called the birth “the second coming of the white buffalo calf.”

“We need to protect the white animals,” he said at the event.

The animal was named "Wakan Gli," which means “Return Sacred” in Lakota, according to the Associated Press.

Saleen Martin is a reporter on USA TODAY's NOW team. She is from Norfolk, Virginia – the 757. Follow her on Twitter at@SaleenMartin or email her at[email protected].