Saving the Cheetah

National Zoo scientist Adrienne Crosier discusses how scientists are using artificial insemination to rescue the species

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How did you start working with cheetahs?
I conducted a research internship at the San Diego Zoo when I was an undergrad and fell in love with conservation and management of endangered species, both in the wild as well as in captive situations. I really wanted to pursue that after I finished my PhD at North Carolina State University so I contacted Dave Wildt at the National Zoo and we spoke on the phone, and I came up to visit many times. We started to formulate some project ideas. The need at the time was more focused on cheetah reproduction and establishment of a genome resource bank—preferentially in Namibia in Africa.

A genome resource bank?
The idea is that we collect genetics in the form of sperm and embryos—in the future we will have oophytes, or eggs—but also skin samples and blood products. So, any frozen genetic materials.

You were recently appointed cheetah research biologist at the National Zoo's Cheetah Science Facility. Can you describe a typical day?
That's a tough one. As we have more and more animals come in to the facility, it will change almost on a daily basis. Right now we have the two adult females, which were down at Rock Creek [Zoo facility] for several years. And so, because they are older individuals and they're very used to being around people, they're actually very easy to work with. So a lot of what we have been doing with them over the last few months is just introducing them to our facility and kind of testing out all the quirks of the new facility, having them in different enclosures and moving them through different parts of the facility, teaching them how to shift through different gates, and learning about their different personalities. We also have a lower course system to exercise the cheetahs on.

I'm assuming the two cheetahs you're talking about are Tumai and Zazi, right?
Yes, Zazi is six and a half and Tumai seven and a half years old. They both came to the National Zoo down at Rock Creek in 2004. Not at the same time—they arrived a few months apart from each other. But one interesting thing about cheetahs is that once they enter a new facility, or a new living situation, often times that will stimulate the females to have an estrocycle and that's actually what happened with both of our females when they first arrived downtown. So they both were immediately receptive upon their arrival into the new facility and they both became pregnant shortly after their individual arrivals. So within about four or five months of each other they were each pregnant and Tumai gave birth to the first litter of cubs ever produced downtown at Rock Creek. That was in January 2005. And then Zazi was just a few months later in April.

So does that mean that they became receptive when they moved to the Cheetah Science Facility?
Actually yes, Zazi did start cycling almost immediately when she came out to the new facility, even though were no boys in sight. So that's a very interesting phenomenon that will happen when you move a female to a new facility. And that's actually a good opportunity to breed females.

So, Tumai and Zazi came to the new facility, became receptive and on February 14th and 15th you artificially inseminated them.
Yes, well, this is actually the ending of a long-term research project, and one of my goals when I went to Namibia for my post-doc in 2002 was to collect and freeze as much sperm from as many cheetahs as I possibly could and that was also part of the genome resource bank. And also at the same time working on improved methods to freeze cheetah sperm and have the most sperm be viable and motile after thawing out. And this part of the research project was actually using some of that sperm that I had frozen back in 2003 in Namibia. We brought that back to the US and then used that sperm last week for the artificial inseminations. So this project actually started about six years ago with my involvement, but I would say 20 years ago with the involvement of JoGayle Howard and Dave Wildt and other more senior folks in the department that have been studying cheetahs for decades.

How many people does it take inseminate a cheetah? What's involved?
There was a team of three folks from our department that were actually doing the surgical part of the laparoscopy and then there were two of us that were doing the sperm thawing and preparing the sperm for the insemination. There was also the veterinary team and then students and volunteers that were assisting with general aspects of the procedures. And then of course curators and keepers and folks that were helping to get the cats in for injections and move them down to the clinic for procedures and things like that, so it takes quite a few people and a lot of organization.

Was Tumai inseminated on one day and Zazi on another day?
They were each inseminated on their own day, but that was more because the injections—the hormonal injections that they get—have to be so carefully timed. The procedures themselves—each procedure only took about two hours, so the anesthesia started about one o'clock in the afternoon and then we were finished by around three.

That must have been very exciting.
Yes, it's very intense. You have to be very organized and coordinated during those two hours because you don't want the female to be under anesthesia any longer than necessary. So just long enough to assess her response and then thaw the sperm and do the actual insemination.

Why did you choose to use sperm from males in Namibia?
Namibia is the largest free-ranging population, and introducing those genetics to the North American population will only improve the genetics of our captive population. Every animal in the North American captive population has a genetic ranking, and so the less related you are to all other individuals, the higher your ranking is and the more recommended you are for breeding. By introducing these wild genes into the population it improves overall diversity—a little bit at a time, but it certainly does improve. And it's also part of the overall research project whereby we are wanting to get to a point where we can introduce genetics to different populations to increase the genetic strength and genetic diversity of individual populations without having them move animals, especially not having to remove free-ranging wild males from their natural environment in Africa. So, using this method, we can just collect sperm and bring frozen sperm back to North America, or Europe or wherever the genetics are needed and the animals stay right there in the wild.


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