Birth Represents a Step Forward in San Diego Zoo Global’s Efforts to Save the Northern White Rhino—and in its Larger Mission to Save Species and End Extinction
San Diego Zoo Global has announced the successful birth of a female southern white rhino calf at the San Diego Zoo Safari Park—the conservation organization’s second rhino born following hormone-induced ovulation and artificial insemination. This calf’s birth also is a milestone, as she is the 100th southern white rhino to be born at the Safari Park.
The mother, 11-year-old Amani, gave birth to the healthy calf at 12:56 a.m. on Nov. 21, 2019, in the Nikita Kahn Rhino Rescue Center. Animal care staff on hand to witness the birth reported that Amani did extremely well during her labor. The calf is nursing well, and mother and calf are bonding in a quiet nursing setting. Artificial insemination of southern white rhinos has rarely been successful in the past; this is only the second successful artificial insemination birth of a southern white rhino in North America. The first was Edward, born to mom Victoria, at the Safari Park’s Nikita Kahn Rhino Rescue Center on July 28 of this year.
“We are so excited to welcome another healthy calf to the rhino crash at the Nikita Kahn Rhino Rescue Center,” said Barbara Durrant, Ph.D., Henshaw endowed director of Reproductive Sciences, San Diego Zoo Global. “We are very pleased Amani did so well with the birth of her first calf, and she is being very attentive to her baby. The calf is up and walking, and nursing frequently, which are all good signs. Not only are we thankful for this 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.”
Amani was artificially inseminated with fresh, chilled semen from southern white rhino J Gregory on July 12, 2018, following hormone-induced ovulation. Collecting and using chilled semen allows for additional generic diversity without having to move animals from facility to facility. White rhino gestation is estimated to be 485 days—but as with any baby delivery, this can differ. Amani carried her calf for 498 days.
The artificial insemination and successful birth of the rhino calf represents a critical step in the organization’s ongoing work to develop the scientific knowledge required to genetically recover the northern white rhino, a distant subspecies of the southern white rhino. Only two northern white rhinos currently remain on Earth and, unfortunately, both are female.
San Diego Zoo Global has a history of expertise with rhino species. With the birth of this calf, there have now been 100 southern white rhinos born at the San Diego Zoo Safari Park, in addition to births of 74 greater one-horned rhinos and 14 black rhinos at the Safari Park. The challenges associated with limited gene pools and severely reduced numbers facing Javan rhinos, Sumatran rhinos and northern white rhinos mean that some form of assisted reproduction may be their only hope for the future. The last Sumatran rhino living in Malaysia died Nov. 23, leaving the current population of this species at fewer than 80 individuals. At the San Diego Zoo Institute for Conservation Research’s Frozen Zoo®, there are currently fibroblast cell lines from two subspecies of Sumatran rhinos: 14 individuals, 3 males and 11 females that could eventually be used in saving this critically endangered species.
“The birth of each rhino calf is a moment for celebration. Although we rejoice with each
birth, we know that the recovery of a species requires collaborative work to build sustainable populations that can thrive in native habitats,” said Paul A. Baribault, president/CEO, San Diego Zoo Global. “We believe in the importance of this work because it has the potential to be applied to save other wildlife, including the critically endangered Sumatran and Javan rhinos.”
In addition to working to save the northern white rhino from extinction, San Diego Zoo Global has been involved in efforts worldwide to save many other species, for more than a century. The organization has been involved in breeding of species that were once on the brink of extinction—including the California condor and the giant panda—and in reintroductions of endangered and threatened species in their native habitats, including as the Hawaiian ‘alala, the Pacific pocket mouse, and the mountain yellow-legged frog. Today, San Diego Zoo Global field programs are working to provide a future for more than 100 rare and endangered species on six continents.
Amani is one of six female southern white rhinos that reside at the Nikita Kahn Rhino Rescue Center. To increase genetic diversity and the number of reproductively fit individuals in North American zoos, these rhinos were relocated to the Safari Park from private reserves in South Africa in November 2015.
Five animal care specialists are dedicated to the full-time care of the six female rhinos. They spend each day building a relationship with and gaining the trust of the animals. The animals are trained, through positive reinforcement, to receive any needed medical procedures, as they could potentially serve as future surrogate mothers for a northern white rhino.
To reach the ultimate goal of successfully producing a northern white rhino, multiple steps must be accomplished. One of the first steps completed involved sequencing the genome of the northern white rhino to clarify the extent of genetic divergence from its closest relative, the southern white rhino. The analysis revealed that they are distinct subspecies. Another step requires conversion of cells preserved from 12 individual northern white rhinos in the Frozen Zoo® to stem cells that could develop into sperm and eggs—a process successfully begun in the laboratory of Jeanne Loring, Ph.D., of The Scripps Research Institute, with details of the process published in 2011.
Reproductive options include artificial insemination, in vitro fertilization and embryo transfer, working with southern white rhinos. When these techniques are perfected, the southern white rhinos would serve as surrogates for northern white rhino embryos. The reproductive system of rhinos is very complex, and there is still much to be learned. There are many challenges ahead, but researchers are optimistic that a northern white rhino calf could be born from these processes within 10 to 20 years. This work may be applied to other rhino species.
There are an estimated 18,000 southern white rhinos remaining in the wild. The southern white rhino is classified as Near Threatened on the International Union for Conservation of Nature Red List of Threatened Species, due to poaching threats and illegal trafficking of rhino horn. Currently, a rhino dies every eight hours in South Africa as a result of poaching.
Amani and her calf will remain in their private habitat for a period of time to allow them to bond. The calf will eventually be introduced to the other rhinos living at the Nikita Kahn Rhino Rescue Center, including her potential playmate, 4-month-old Edward.
On any given day, visitors to the Safari Park may be able to see one or more of the southern white rhinos living at the Nikita Kahn Rhino Rescue Center from the Africa Tram. The public can help support San Diego Zoo Global’s rhino conservation efforts through the San Diego Zoo Global Wildlife Conservancy at EndExtinction.org/Rhino or EndExtinction.org/Amani.
