From their Facebook.
"It is with heavy hearts that we announce that our eldest polar bear Arki passed away today. She was a great ambassador for her species educating visitors in Ilinois at the Brookfield Zoo and these last few years in Louisville. Our keepers and staff made a bond with her so it is a tough day. Arki was 28 and was the first polar bear to inhabit Glacier Run. Polar bears can live into their early 30s in managed systems, however most live into their mid 20s. Arki flourished her last few years here. Arki taught her keepers something we didn’t know about bears – that iceberg lettuce could be a favorite food of a polar bear! Thank you, Arki, for being a great ambassador for an iconic species."