NASHVILLE, Tenn. (WKRN) — The Nashville Zoo is working to preserve one of the world’s rarest cat species with a special breeding process that biologists say will one day help them reinforce wild populations.

The Nashville Zoo has partnered with zoos around the world for over two decades to develop collaborative breeding programs and field monitoring projects for clouded leopards in Thailand. And in 2017, Nashville made history with the birth of a male clouded leopard named Niran.

His birth was the result of a collaboration with the Smithsonian’s National Zoo and Conservation Biology Institute in which researchers conducted an artificial insemination procedure with semen that had been frozen and thawed.

“The collaboration across institutions is critical for all of our endangered species’ populations, so it’s important that we work together for the betterment of the species to advance the research,” said Adrienne Crosier, a Biologist at the Smithsonian Conservation Biology Institute. 

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Nashville Zoo hopes to birth second cub through artificial insemination

While Crosier said the success rate of the procedure is still low, researchers are continuing to expand their knowledge on the biology of clouded leopards, and now they are hoping to welcome at least one new cub born of artificial insemination at the Nashville Zoo next year.

A 3-year-old clouded leopard named Jewels was one of four females artificially inseminated using frozen and thawed semen this week. Having already birthed two cubs last year through a natural mating process, biologists said Jewels was ideal for the procedure.

Adrienne Crosier talks about the artificial insemination process (Photo: WKRN)

Before conducting the procedure, biologists observe the clouded leopards’ genetics to see which males and females are a good match. That helps ensure the process is not only expanding the captive population, but making it more diverse.

“We have some sperm samples with us that are from males that passed away several years ago, and those males died before they reproduced,” Crosier said. “So, if we can get those genetics in the population, it’s like resurrecting those males.”

While more than 42 clouded leopards have been born without artificial insemination at Nashville Zoo since 2009, the procedure makes the process smoother and more effective.

Dr. Pierre Comizzoli explains the importance of the artificial insemination process. (Photo: WKRN)

Dr. Pierre Comizzoli, a Research Veterinarian at the Smithsonian Conservation Biology Institute, said clouded leopards like most big cats are very difficult to breed. Many are sensitive to auditory and visual disturbances, which can increase stress during captive breeding programs.

“They are very picky, they need a special environment, there needs to be also chemistry between the male and the female,” he said. “Unfortunately, sometimes the chemistry doesn’t exist between two individuals that really need to produce offspring for the survival of the species because they are not genetically related.”

Once a match is selected and sperm is collected from the male clouded leopards, biologists use hormones to induce ovulation. The animals are then sedated and injected with the sperm sample.

With more than 40 years of research dedicated to clouded leopards’ reproductive biology, Comizzoli said the procedure has gradually become more efficient. A newer technique allows them to deposit semen into the oviduct where the eggs normally rest after ovulation.

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“We started with very thorough studies of the reproductive biology of those animals,” he said. “Because cats are not like cows, they’re not like dogs, they’re not like rodents, they have their really special biological reproduction that we had to understand.”

The first successful clouded leopard insemination was performed at Nashville Zoo in 1992 by Smithsonian scientist, JoGayle Howard, and Nashville Zoo President, Rick Schwartz. Then in 2015, Comizzoli successfully birthed two cubs at the Khao Kheow Open Zoo in Thailand.

“We had two cubs born from that artificial insemination and then we repeated that here at the Nashville Zoo,” Comizzoli said, referring to the birth of Niran in 2017.

The procedure conducted on Jewels on Tuesday “went very well,” Comizzoli said. He added that the response from the clouded leopard’s ovaries was “exactly what we were looking for.”

Most clouded leopards only need about 24 to 48 hours to rest and recover from the procedure. Then, it is a waiting period to see if the procedure was successful. Croiser said biologists could know if a pregnancy is viable in as soon as six to eight weeks using ultrasound.

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Why artificial insemination is necessary to species’ survival

The research and management of clouded leopards in captivity also serves value to their relatives in the wild. Comizzoli said their elusive nature makes it difficult to get an accurate count, but there are only an estimated 10,000 clouded leopards left outside of captivity.

“We know that they are endangered because we know that they are poached and over hunted, unfortunately,” he said. “And that’s unfortunately the same situation for a lot of endangered species sharing the same habitat.”

Clouded leopards are considered vulnerable to extinction by the International Union for the Conservation of Nature, and because the captive population is not self-sustaining, Comizzoli said expanding that population is necessary to the species’ survival.

“Protecting the natural habitat is priority number one to save species,” he said. “But when you reach the stage where you have the possibility to reintroduce animals into this natural habitat, then after that, you need to rely on collections that you have in zoos or in breeding centers.”

(Photo: WKRN)

The environment also allows researchers to more closely study the elusive animals. Comizzoli said similar research into reproductive biology and assisted breeding programs is already being applied to many other species, like cheetahs.

“That’s why the zoo is very, very important. Also, all the knowledge that we are accumulating by studying the species, they are easily available, we can sedate them and study them,” Comizzoli said. “This would be completely impossible in the wild.”

Eventually, Crosier said captive populations may be used to help reinforce populations in the wild and reintroduce certain species to an area of their natural habitat where they have completely disappeared.

“Every cub we produce is important to the overall population, not only in this country, but on a global scale,” she said. “So many of our endangered species are losing numbers and losing habitat in the wild. We’re having to manage these species more on a global level with these meta populations– these small, managed populations worldwide.”