Descriptions of her species read like something out of a superhero comic book:

Stealthy at night, a piercing gaze, and dramatic in flight.

Mostly though, Uhu the Eurasian eagle-owl will live on in memory as “a huge, sweet owl,” said Karla Bloem.

Tens of thousands of people witnessed Uhu catch air and fly during presentations at the International Owl Center in Houston, Minn., where Bloem is executive director.

Bloem announced Uhu’s death Monday. The owl, among the center’s teaching birds, had severe heart disease. The Raptor Center diagnosed atherosclerosis, or hardening of the arteries, during a regular wellness visit in January. It was a surprise, Bloem said.

The bird was 13 years old – young by Eurasian eagle-owl standards. Bloem said the species can live 30 to 40 years.

The diagnosis arrived at a time when Uhu (pronounced uw-who) already was slowing down, she added. Uhu hadn’t “come to work” for a few years. “It’s a disease for old birds, so we’re scratching our heads as to what happened.”

Eurasian eagle-owls’ habitat spans Europe and Asia, according to the owl center. Uhu was born in captivity and was sent to the center in 2015 from a Martha’s Vineyard, Mass., man who had permits to work with wildlife.