Rilu, an 11-year-old snow leopard, struggled with Covid-19 induced pneumonia before death, according to a post on the Miller Park Zoo verified Instagram account.
"Rilu arrived at the Miller Park Zoo in 2011 from the Oklahoma City Zoo," the post said. "During his time here, he produced seven living offspring that are now part of the Species Survival Plan (SSP)."
"He made the Miller Park Zoo one of the leading institutions in the world in producing Snow Leopard cubs."
"Rilu's personality and beauty will be missed by guests and staff, but he will not be forgotten."
Snow leopards are a vulnerable species, according to the World Wildlife Fund. With an estimated population of 4,000 to 6,500, the main threats to their survival are hunting, habitat loss and the climate crisis.
Wildlife photographer Joel Sartore, who captured Rilu on film, paid tribute to the snow leopard in a post on his verified Instagram account.
"We are very sad to share the news that Rilu, an 11-year-old snow leopard @millerparkzoo, has died from COVID complications," Sartore said.
"Snow leopards are proving extremely susceptible to the disease, and it's often fatal. If you haven't received a vaccination and booster yet, please do so. It's more than just human lives that are at stake. Thank you."
Cases of zoo animals infected with Covid-19 have been previously reported. In December, two hippos tested positive for Covid-19 at a zoo in Antwerp, Belgium. A month earlier, three snow leopards died at the Lincoln Children's Zoo in Nebraska, due to Covid-19 related complications.
"I love that the legacy of Rilu will live on in the Photo Ark. Rilu will engage and astonish the world for many years to come," said Jay Tetzloff, zoo superintendent, according to the Miller Park Zoo Instagram post.