Dmitri is a 380-pound Amur tiger, and as he lumbered across the grounds of his compound at the Philadelphia Zoo today, it was difficult to imagine him leaping an 18-foot wall.

But officials think that's what may have happened at the San Francisco Zoo on Christmas when a highly endangered tiger turned highly dangerous, escaping its pen to kill one person and maul two others. Today, executives at some local zoos were bewildered that such a big cat was said to have leaped so high.

Andy Baker, who oversees the care of animals at the Philadelphia Zoo, said he would be very surprised if it were true. "That's just outside of all of our historical experience with tigers at zoos across the world," he said.

Baker said that the Philadelphia Zoo is safe, and that its tiger display has won acclaim from groups that consider safety in their evaluations. "We have a great staff that thinks about safety every day," he said. The tiger enclosure includes an outdoor area with 16-foot walls topped with a 3-foot overhang, reminiscent of the giant screens erected behind home plate at baseball parks.

Few people were visiting the zoo on a gray, chilly Wednesday afternoon. None said they were worried about the possibility of a tiger escape, and many had not heard of the attack in California now making news around the world.

Kelly Shaw, curator of the Cohanzick Zoo in Bridgeton, N.J., which has two white-tiger brothers, also was surprised by reports that the cat scaled a wall or leaped from its enclosure, because tigers are heavy and not known for being good climbers.

At her zoo, "things are going on as normal, but when something like this happens, it just kind of puts you on your toes," Shaw said. "Instead of triple-checking my gates, I'll quadruple-check them."

The San Francisco Zoo was closed to visitors today as investigators tried to determine the circumstances of the attack. The tiger, a 300-pound female named Tatiana, was the same animal who ripped the flesh off a zookeeper's arm just before Christmas 2006.

The zoo's director of animal care and conservation, Robert Jenkins, could not explain how Tatiana escaped. The tiger's enclosure is surrounded by a 20-foot-wide moat and 18-foot-high walls, and the big cat did not leave through an open door. "The animal appears to have climbed or otherwise leaped out of the enclosure," he said.

The tiger was killed by police summoned by a 911 emergency call.

Police were gathering evidence from the tiger's enclosure as well as accounts from witnesses to determine whether someone either accidentally or intentionally helped the tiger escape.

"It really is a zookeeper's nightmare," said Shaw, of the Cohanzick Zoo. "You want people to come in and learn about the animals, and enjoy their visit. You certainly don't want them getting hurt."

At her zoo, tigers Shiva and Ganesha reside in a compound that includes an indoor den and an outdoor, fenced enclosure. The compound was built to house the tigers, who arrived as cubs 10 years ago.

The interior of the cages at two public-viewing windows is sodded with "hot grass" - a material that looks like grass but gives the tiger an electric charge when stepped on. The zoo was not concerned about the animals' breaking out; rather, they tended to urinate on the glass.

The zoo is not large enough to display both tigers at once, so they go outside one at a time for half the day. Shiva, who like his brother weighs about 400 pounds, was outside when Shaw came to the phone today.

"Is my tiger behaving as though he wants to get out? No," she said. "They're creatures of habit, [doing] what they consider to be normal, just like we have our routines. . . . They treat it as though it's their territory; they patrol it. They mark it."

At the Cape May County Zoo, director Hubert "Doc" Paluch, a veterinarian, said administrators were not conducting additional checks on the fenced confines of their tiger, a 6-year-old, 500-pound Siberian named Rocky, one of the zoo's biggest attractions. They are confident that the compound was secure, he said.

"Our protocols are in place," he said. "We check the facility on a daily basis for any malfunctions. It's checked when the keepers come in and before they leave."

The Philadelphia Zoo's Baker said he was shocked by the news from San Francisco because it is rare to have a visitor injured at a big U.S. zoo.

"Tigers have been held safely in zoos for many, many, many years," he said.

There are about 150 Amur tigers in the United States. They are from the Amur Valley, named for the river that snakes through the Russian far east. Almost all Amur tigers are bred in captivity. There are only about 400 left in the wild.

Tigers in captivity may have slightly diminished physical capabilities because they no longer perform the arduous feats of their wild counterparts. Thirteen-year-old Dmitri, while in good shape, is also somewhat heavier than a wild cat.

"We're confident of the safety systems and the facility design," Baker said, "and people can feel very comfortable bringing their families here and not worry about looking at a tiger without glass or mesh in between."

Contact staff writer Jeff Gammage at 610-313-8110 or jgammage@phillynews.com.
This article contains information from the Associated Press.