San Diego: The San Diego Zoo Safari Park's 99th baby southern white rhinoceros was born recently, but the arrival of "Edward" sparked much more widespread interest than the previous 98 births of his subspecies.

That's because Edward's conception occurred not through natural mating but via artificial insemination. He is the first southern white rhino born through artificial reproduction in the United States.

Day-old southern white rhino calf Edward stands beside its resting mother, Victoria, at the Nikita Kahn Rhino Rescue Centre at the San Diego Zoo Safari Park in Escondido, California. Credit:AP

The world's five rhino species all live under severe threats to their survival, including from poaching and shrinking habitat. Some species, such as the greater one-horned rhino, number in the thousands and are considered critically endangered. The Javan and Sumatran rhinos of Asia, by contrast, are near extinction.

Some rhinos in human care don't reproduce well, which complicates efforts to sustain these important insurance populations. Scientists have worked for years to develop reliable means of artificial reproduction, with limited success. Examples are scarce: a dozen years ago, a southern white rhino was born through artificial insemination in Budapest, and a greater one-horned rhino was born with such help in Miami in April.