PROVIDENCE, R.I. (AP) – Trixie, the lone remaining polar bear at Roger Williams Park Zoo, has died.

The 18-year-old female bear died on Saturday as zoo staff prepared her for a temporary move to the Indianapolis Zoo. Staff had sedated Trixie and had moved her to a protective carrier. They then gave her a “reversal” drug, designed to wake Trixie for the journey.

“She was coming out of it great. She was picking up her head. Everything seemed to be going well,” Roger Williams Park Zoo director Jack Mulvena said. “All of a sudden, 10 or 15 minutes later, she inexplicably stopped breathing.”

An exam given to her after administering the sedative showed she was in excellent health, Mulvena added.

A necropsy showed the bear had no obvious health problems, said Cheryl Cullion, the doctor who led the procedure. Trixie had been through similar sedations a dozen times before – most recently in January – without any complications, Cullion added.

“She was for all intents and purposes a healthy bear,” Mulvena said.

A polar bear’s life expectancy is 20 to 30 years, but they live longer in captivity, Mulvena said.

Trixie was born in captivity, and had been at the Providence zoo since 1989. While there, she gave birth to four cubs. The surviving two are in zoos in Tucson, Ariz. and Detroit.

Mulvena called her a typical polar bear who loved to swim and whose favorite treat was peanut butter.

Roger Williams is doubling the size of its polar bear exhibit. The new exhibit, scheduled to open in 2007, is expected to include a wider variety of habitats. Trixie was supposed to return to the new quarters.