Zero, the polar bear that tumbled into a dry moat at his zoo enclosure more than two weeks ago, was rescued Thursday morning after zoo officials anesthetized him and hoisted him out with a crane.

Zero was sleeping off the effects of the tranquilizer Thursday in a nonpublic enclosure at the Milwaukee County Zoo and would remain there at least until Saturday, zoo spokeswoman Jennifer Diliberti said.

"I think the zoo staff was just concerned that this was going on too long," she said. "He's resting now and is being monitored by the staff."

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Zero was playing with a toy on Oct. 13 when he stumbled off the edge of his exhibit.

He landed unhurt on netting suspended a few feet above the moat floor. Zoo officials then cut the net's cables so the 1,100-pound bear could drop safely to the bottom of the concrete moat.

His position was low enough that visitors, who are separated from the enclosure by a fence, were never in danger, the zoo said.

Officials hoped Zero would use a nearby stairway to climb back to his exhibit, but he seemed content to remain where he was.

Keepers made sure he had water and shelter, but they provided only half his normal food rations in the hope that hunger would drive him from the moat.

No such luck.

As the days turned to weeks, keepers began to worry about the long-term effects of denying Zero his full menu, zoo director Chuck Wikenhauser said.

"To put him on half-rations for the short-term is one thing, but it's probably not best for him long-term as far as the bear's health goes," he said.

A veterinarian confirmed Zero was unhurt when he was lifted from the moat, Wikenhauser said.

With the net cut down, zookeepers had to remove their other polar bear, a female named Snow Lilly, to a private enclosure. The desire to return her to the primary exhibit was another factor in Zero's rescue, Diliberti said.

Zoo officials tried earlier this week to trap Zero, lowering a crate filled with polar bear goodies — apples, peanut butter and herring — into the moat.

The crate door was designed to close when Zero entered. Although he sniffed the treats, he never went in far enough to get trapped.

"By yesterday, he was becoming bored of that," Wikenhauser said, "so we made the decision late yesterday this was the time to get him out."

Fifteen years ago, the 19-year-old polar bear fell into the moat and remained there nine days before climbing out on the stairs.

Wikenhauser said that was probably too long ago for Zero to remember how he escaped. He also said Zero, who could live another 10 years or more, has probably lost some of his agility.

With the enclosure empty for the next few days, zoo officials planned look at modifications that could help a bear extricate itself from the moat in the future.

Keepers were considering making the staircase easier to navigate, as long as it wouldn't tempt the bears to walk down into the moat, Wikenhauser said.