SAN DIEGO —Victoria the southern white rhino is now happily bonding with her healthy newborn son at the San Diego Zoo Safari Park. And with that birth on Sunday, the prospects for rescuing their nearly extinct kin have brightened.

The successful pregnancy of Victoria is a dry run for an ambitious program to bring back the closely related northern white rhino using stem cell technology. Only two of this subspecies are alive in the world, both of them females too old to give birth.

Victoria was artificially inseminated on March 22 of last year with semen from southern white rhino father Maoto. This is the first time the procedure has been performed successfully in North America, the zoo says. Mother and the still unnamed son are now bonding at the Safari Park’s Nikita Kahn Rhino Rescue Center.

“All of us at San Diego Zoo Global are elated with the arrival of this special rhino calf,” said Barbara Durrant, director of reproductive sciences at San Diego Zoo Global. “… Not only are we thankful for a healthy calf, but this birth is significant, as it also represents a critical step in our effort to save the northern white rhino from the brink of extinction.”

That process will take many years, and the zoo has other hurdles to overcome before it succeeds.

Victoria and five other southern white rhino females are bearing children to prove their ability to have healthy offspring. At the same time, they are being prepared to accept implanted embryos of northern white rhinos created from stem cells.

Once those embryos are ready, the plan is to transplant them into females proven to carry healthy babies to term. To the rhino moms, the embryo transfer will appear much like artificial insemination. They have already been trained to accept intimate examinations through positive reinforcement, mainly food.

The embryos themselves are to be created from cryo-preserved northern white rhino tissue from the Frozen Zoo at the Safari Park. This tissue is being turned into stem cells. These stem cells will eventually be converted into gametes, sperm and egg cells. These cells will then be brought together to form embryos, which will be implanted into the surrogate mothers.