Seven cheetah cubs, coated with smokey gray hair and about the size of an American football, were born at the National Zoo’s Smithsonian Conservation Biology Institute (SCBI) in Front Royal, Virginia on July 9. The cubs are a first for parents Erin and Rico, yet, the litter itself was the 12th SCBI has seen since 2010, bringing the grand total to 53.
“It is really exciting to have such a large and healthy litter of cubs, especially from first-time parents,” said Adrienne Crosier, a biologist and manager of SCBI’s cheetah reproductive and research program. “A global self-sustaining cheetah population in human care is becoming even more important with the continued decrease of animal numbers in the wild.”
Population estimates for wild cheetahs is currently about 7,100. Due to habitat loss, human conflict and illegal trade, the cheetah’s habitat range is confined to east and southern areas of Sub-Saharan Africa and a small portion of northeastern Iran, just nine percent of its historic area. To make matters worse, the infant mortality rate for cubs born in captivity is about 30 percent and up to 90 percent in the wild.
One of the main issues contributing to the decline in global cheetah population is the lack of genetic diversity. About 10,000 years ago, cheetahs experienced a population bottleneck following the last ice-age. The surviving cheetahs repopulated, but had limited genetic diversity in their offspring. The effect: susceptibility to disease, low-fertility, genetic mutations and physical homogeneity.
The low-levels of genetic variation have been particularly troubling for breeding cheetah populations in captivity. Since 2012, a group of organizations—SCBI included—have created the Breeding Centers Coalition to address these genetic challenges and produce more cubs with higher genetic diversity.
This litter is particularly important to the population of cheetahs living in zoos because the mother, Erin’s, genes are not well represented in cheetahs living under human care in North America. Almost all the cheetahs in the United States descend from two cheetah subspecies, one from South Africa and the other from Namibia. Additionally, the cubs’ father, Rico, was specifically brought in at the ripe age of nine to mate with Erin.
“We want to make the best matches possible,” Crosier said. “We need these populations to survive long into the future.”
Across nine different breeding centers, researchers have a catalog of approximately 360 cheetahs. With full knowledge of their ancestry, scientists are able to determine the best mates for breeding genetically diverse litters, according to Crosier.
To further counter population decline in the wild and in captivity, SCBI researchers are using a new fecal hormone method to determine pregnancy in cheetahs. Cheetah pregnancies typically last three months and, usually, it is extremely difficult for researchers to determine whether a female is pregnant until at least 55 days into the pregnancy, in part because cheetahs frequently experience pseudopregnancy, a condition where non-pregnant females exhibit behavior conducive to pregnancy after mating.
Because, pregnancy diagnosis is a crucial element in the rehabilitation of small populations of threatened animals, SCBI has identified a protein, immunoglobulin J (IGJ), that is more abundant in the feces of pregnant cheetahs during the first month of gestation to help identify pregnancy. Fecal samples from Erin will contribute to creating a non-invasive pregnancy test to help researchers make critical decisions about preparing for birth and/or allowing them to rematch female cheetahs with new mates.
The seven cubs will likely move to other zoos or facilities accredited by the Association of Zoo and Aquariums once they are mature. But, for now, the cubs are under tight watch from their new mother, who only leaves the cubs for 10 or 15 minutes max.
“Every mother is different, but I would say Erin is on the protective side,” Crosier said. “She gave birth to a litter twice the size of an average litter, she’s got a lot on her plate.”