The city is confident the tiger cages at the Honolulu Zoo are sufficient to prevent a tragic escape such as the one that resulted in the death of a teenager in San Francisco on Christmas Day.

Honolulu Zoo tigers would have to scale a 15-foot vertical wall, then bend backward and crawl another four feet at an angle before they could reach the cage opening.

"In our case, when we evaluate our risk, we feel that it's very, very minimal — if anything, nonexistent," said Sidney Quintal, director of the city Department of Environmental Services.

The American Zoo and Aquarium Association recommends that tiger pen walls be at least 16 feet, 4 inches high.

"We've exceeded what the AZA would have recommended," Quintal said.

By contrast, the cage the tiger at the San Francisco Zoo escaped from was about four feet below the AZA recommendations, although the zoo itself was in good standing with that accrediting organization.

The tiger that killed 17-year-old Carlos Sousa Jr. and mauled his friends, Paul Dhaliwal, 19, and Kulbir Dhaliwal, 23, on Christmas is the same tiger that mauled a zookeeper last year.

After the attack on the zookeeper, the San Francisco Zoo added steel mesh over the bars, built in a feeding chute and increased the distance between the public and the cats.

Investigators are looking into whether the victims in the Christmas attack might have provoked the tiger or ignored warnings not to taunt the animals.

"Even if they provoked the tiger, a reasonable person would believe that the tiger could not escape. That's what you count on when you go to the zoo. You count on the idea that the animals cannot reach you," said Rory Little, a professor at the University of California's Hastings College of the Law.

The Honolulu Zoo has three Sumatran tigers, two of which are housed in a new enclosure. Both enclosures have non-imposing steel barriers to create as close to a native habitat as possible, but they're still formidable cages with overhangs that angle inward to make it nearly impossible for a 350-pound tiger to escape, Quintal said.

After running into problems with its accreditation last year, the zoo reviewed all of its exhibits to re-establish itself in good standing. It was fully accredited again in March.

Currently, the zoo is working to ensure all its facilities meet or exceed American Zoo and Aquarium Association's guidelines.

"What we've done is we've undertaken a review of our tiger facility first. We've taken every precaution. We're even trimming back any foliage, anything that could remotely come through," Quintal said.

The zoo is focusing in particular on predator cages. "If a zebra got out, I don't consider that a serious concern, but if a rhino got out, those guys have got tempers so it's terrible from our standpoint," Quintal said. "We really have to review all of that."

While a fallen tree led to a brief and uneventful chimpanzee escape about a decade ago — zookeepers were able to scare the chimps back into their cage with a fire extinguisher — no one at the zoo could remember a harmful animal escape there.

The 1994 escape of Tyke, a traveling circus elephant, during a Blaisdell Arena performance is probably the state's most dramatic animal rampage. The elephant mauled its groom, crushed and killed its trainer and ran loose in Kaka'ako for a half-hour before being shot to death.

The Honolulu Zoo has that in mind as it works on a new elephant enclosure that will hold a bull elephant for mating purposes.

"As we move into finishing our elephant habitat, we are taking every precaution to putting in the right barriers," Quintal said. "We will be taking extreme precautions in completing the habitat."

Reach Treena Shapiro at tshapiro@honoluluadvertiser.com.

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