After the longest pregnancy ever for an African elephant in captivity -- 688 days or almost 23 months -- Moja successfully gave birth to a healthy female elephant calf at 5:30 a.m. yesterday at the Pittsburgh Zoo & PPG Aquarium.

The 25-year-old mother, Moja, and her new, as-yet-unnamed, 247-pound baby are both healthy, bonding well and starting to nurse, according to Barbara Baker, president and chief executive officer of the zoo.

After the record-length pregnancy, the baby elephant was born after a labor of 20 minutes.

"The new elephant is a vigorous calf who got up and began walking on its own just 18 minutes after it was born," Dr. Baker said. "Moja is a superb mom. We couldn't ask for better behavior. She knew just what to do when she went into labor and has been a very protective mom."

The birth, which took place in the elephant barn with at least three other members of the zoo's elephant herd pacing anxiously in a separate pen next to the birthing pen, was the zoo's second successful elephant birth in less than a month.

On July 9, Savannah, another 25-year-old African elephant, gave birth to a 286-pound female named Angelina. She is healthy and is gaining weight at a rate of two to three pounds a day.

"This will certainly be a balancing act with two baby elephants," said Willie Theison, the zoo's elephant manager. "They will keep us on our toes."

As crowds lined up outside the elephant barn to view Angelina through wide glass windows, the zoo kept the new calf under wraps on the other side of the barn yesterday the to allow the baby to bond with its mother and other members of the herd.

Zoo visitors could get their first glimpses of the new baby elephant tomorrow or Monday at the earliest, Dr. Baker said.

Zoo officials allowed no photographs or video to be taken yesterday morning and had no plans to give 2,300 attendees at a fund-raising gala last night a sneak peak at the newest pachyderm. The zoo did release photographs and video taken by zoo personnel that showed the new elephant, its legs wobbly and rubbery, tottering next to its mother, shortly after it was born.

Amos Morris, the zoo's curator of mammals, said the new baby elephant is shorter and rounder than Angelina was when she was born, and is making attempts to nurse, some of them successful.

"The mother has the milk," Mr. Morris said. "Once the baby figures out what body part she should attach herself to it will be OK."

The pregnancy beat the previous record length of 674 days, but Dr. Baker said it had zookeepers worried. They had said that the births of both baby elephants were imminent in early June.

"This baby cooked for 688 days and we were getting worried that something had gone wrong," Dr. Baker said. "But as you can see we have a calf that is very vigorous and very strong."

Dr. Baker said zookeepers don't know why the pregnancy took so long, but speculated that Moja may have held off giving birth until the excitement from Angelina's birth settled down.

This month's elephant births in Pittsburgh were the first at the zoo since Savannah delivered a male elephant named Callee in September 2000. Moja successfully gave birth to Victoria in September 1999.

Jackson, the zoo's prolific bull elephant, is the father of all four elephant calves born in Pittsburgh. His semen was also used to impregnate an African elephant at the Atlanta Zoo that is due in July 2009. He is one of three breeding bull elephants in the country.

Because of technological and care advances at zoos, the mortality rate for African elephants in the United States has decreased over the last decade from 40 percent to 15 percent.