Spring has brought the births of two separate litters of adorable baby cheetah cubs at the Smithsonian Conservation Biology Institute (SCBI) in Front Royal, Virginia. This was no accident. Smithsonian's scientists have a breeding program designed to preserve this endangered species through just the right pairings of cheetahs and perfect timing that allows the cubs to thrive.
One litter of five cubs was born healthy, but a second litter of seven cubs born to a different mother included two undersized cubs that died soon after birth. This is common among litters that large. The second female that gave birth at SCBI this spring also happens to be the mother of the first female who gave birth.
Wild cheetahs may go into estrus and become pregnant at any time throughout the year. Unlike wild cheetahs in warm climates, the captive animals kept in outdoor enclosures in Virginia could find their cubs at risk of freezing in the winter. For that reason, biologists only allow the cheetahs to breed when the resulting cubs will arrive in the spring to early fall.
Only around 7,100 cheetahs are thought to be living in the wild. About 1,800 captive cheetahs are part of an international species survival plan that is designed as a bulwark against extinction while preventing inbreeding. Adrienne Crosier, a cheetah biologist at SCBI, is also the program leader of the cheetah's species survival plan. A total of 57 zoos participate in the program, including eight where cheetahs are bred.
“We are aiming for 35 cubs a year so we can become a self-sustaining population,” says Crosier. “We actually have enough animals and really good gene diversity... only about 20 percent of our population is reproducing. We have to make sure that all of the different lines are represented.”
Cubs born at SCBI will serve several purposes. Some will be selected to be part of breeding programs that preserve the species with as much genetic health and diversity as possible. Others will go to zoos for display purposes.
By studying the genomes of modern cheetahs, scientists know that cheetahs were subjected to a genetic bottleneck about 10,000 years ago. Whether the danger was disease, competition, habitat transformation or a combination of issues, cheetahs narrrowly avoided extinction and then rebounded with low genetic diversity. This has put them at especially high risk of inbreeding as their numbers once again dwindle in the wild due to habitat fragmentation and poaching. Physical signs of inbreeding have become common.
“Some of the more obvious things we see are very low levels of sperm,” Crosier says. “Males only produce 20 percent normal sperm. Quality is low compared to other mammals. Interestingly, all cheetahs have that problem. We see some teeth abnormalities, crowded incisors. We see a lot of kinked tails, especially among wild cheetahs.”
Biologists hope that careful pairing of cheetah parents can eventually eliminate some of these deformations in the overall population.
The cubs will spend at least 18 months growing up in SCBI's spacious enclosures before they will be sent to other zoos.
“Our goal is to have at least one litter each year” at SCBI, Crosier says. “We definitely can't keep them all! We don't have the space.”
Once weaned, the cubs will be fed a commercially produced beef-based mix of meat. They will also be provided with bones to keep their teeth clean and their jaws healthy. Each cheetah is also fed a whole rabbit once each week.
As cute as they are, nobody but their mother gets to play with the cubs or cuddle them. The cubs are regularly picked up only to be weighed and medically examined. All ten of the surviving cubs from these litters are healthy and growing well.
SCBI is the National Zoo's 5,000 acre research facility in the foothills of the Shenandoah Mountains. Threatened and endangered wildlife including red pandas, black-footed ferrets and clouded leopards are raised there.