The three Sumatran tiger cubs born May 2 at the National Zoo got their first exposure to adoring crowds yesterday when they were let loose to romp and stalk in their yard a day before their official debut.

The three male cubs go on public view today from 7:30 to 9:30 a.m. at the lion and tiger exhibit near the lower end of the zoo. As they get bigger and stronger, they will spend more time in the yard.

"They've only been out a few times before," said keeper Marie Magnuson, who has been helping the cubs adjust to zoo life. "They play pretty rough, but they get along."

In about three years, the cubs will be split up and sent to other zoos for breeding. Sumatran tigers are an endangered species, found only on their Indonesian island. Fewer than 500 exist in the wild, and 200 live in zoos.

The cubs were named by the public in a contest sponsored by Friends of the National Zoo. The names are Indonesian: Marah, meaning fierce; Besar, meaning mighty; and Jalan, meaning journey. The three, who now weigh about 30 pounds each, are fed horsemeat with vitamins and minerals. As adults, they will reach 250 to 300 pounds.

Until their preview yesterday for the media and FONZ members, the cubs had been kept behind the scenes to give them a chance to bond with their mother and get used to their surroundings, zoo officials said. They also needed to get big enough to climb the stairs to their outdoor yard.

Keepers let them into the yard for the first time about a week ago, without their mother. They wanted to make sure the cubs could negotiate the enclosure -- and get out of the moat if they jumped or fell in.

"They had to be able to swim," said Magnuson, noting that all three passed the swimming test. "Marah was doing the butterfly."

In typical cat fashion yesterday, the siblings playfully pounced on one another and separately nosed around their new quarters. One tumbled down the stairs to their indoor space, unhurt; another spent most of the time hiding in the bamboo.

Three cameras and TV monitors help keepers keep tabs on the cubs while they are in their yard -- and let the public watch their activities on the zoo's Web site. But most of the caretaking is being left to Soyono, their mother.

"Soy is a terrific mother," Magnuson said. "She's as patient as she can be. We just let her do what she knows how to do."

With these births, the zoo has seven Sumatran tigers, representing three generations. Soyono's mother, Kerinci, is on exhibit, as is Soyono's mate, Rokan. The cubs also have a brother, Berani, born to Soyono in 2001.

Soyono leads her cubs around their outside surroundings the day before their official public debut. Media representatives and zoo supporters were allowed an early glimpse of the tigers.The cubs proved perfectly comfortable roughhousing in front of the cameras.One of the cubs reaches out for Soyono. Sumatran tigers are an endangered species; fewer than 500 exist in the wild, and about 200 live in zoos.