By John Kelly
Monday, May 21, 2007

Behold the giant elephant shrew, an African mammal about the size of a kitten. It has a long, ratlike tail, a fetching auburn coat and a long, twitching nose that makes it look like an anteater.

Our own National Zoo was the first zoo to figure out how to keep giant elephant shrews alive in captivity. The Cincinnati and Philadelphia zoos were the first to figure out how to breed them. The secret is to strew the bottom of their enclosure with leaf litter. Once you do that, as Don Moore, the National Zoo's associate director for animal care, said, they start "cranking the babies out -- boom, boom, boom!"

But as cute as that might sound -- an explosion of baby giant elephant shrews! -- it can be too much of a good thing. And so, at a time when Washington is fixated on whether Mei Xiang has a steamed bun in the oven, I went to the zoo to see how they prevent pregnancies, not cause them.

There was a time when zoos didn't have to worry so much about such things. Before the zoo renaissance of 30 years ago, many displays consisted of a single animal in a concrete cage. There wasn't much mischief it could get up to, in there by itself.

Then came the move to more natural settings. Put a bunch of giant elephant shrews (or orangutans or poison dart frogs) together in exhibits that approximate their natural habitat and before you know it they're acting like, well, animals.

"Once you get the habitat right, you get to your carrying capacity very, very fast," said Don. And that's not good. Plus, it's against the rules. Accredited zoos must abide by written Species Survival Plans that dictate which animals may breed and with whom.

"It's all very, very detailed," Don said. "That goes all the way down to dart frogs. I don't think it's gotten to fish yet." (Which is a good thing, because some species of fish can switch their sex. If you have a habitat full of boy fish, the largest boy fish just changes into a girl fish. I have to wonder if that's at all awkward for everyone involved.)

The simplest guard against pregnancy is the one employed by suspicious fathers in countless fairy tales: Keep the males separate from the females. But there are times when the heart just won't be denied. At a zoo he previously worked at, Don put a male goat on the other side of a wire fence from the females. After the females got pregnant, it was clear that a fence won't stop a determined goat.

When animals can't be separated, the National Zoo uses methods familiar to any human hoping to keep from getting knocked up.

"It's real easy to give a gorilla a birth control pill," Don said. Zookeepers just stick the same sort of pill humans use inside a daily food treat. Other apes -- orangutans, gibbons -- get Norplant, the chemical implant that's positioned under the skin. Some have had their tubes tied.

A few species can handle things just fine on their own. Meerkat moms, for example, produce just enough baby meerkats to achieve a comfortable density for their habitat. Then they simply stop having babies.

I've just gone all squishy inside thinking of itty-bitty baby meerkats. Don, baby animals are so cute. Can't we have more of them?

"Baby animals are cute, but we have to manage our populations responsibly," he said. "It's not about producing baby animals for the sake of producing baby animals for the visitor. It's about producing baby animals when the population needs a boost . . . or when it's an endangered species."

Which brings us to Minnesota, the zoo's male Przewalski's horse, a Mongolian species extinct in the wild. Scientists didn't think Minnesota had very valuable genes and so when he lived at a previous zoo he was given a vasectomy. Recently, it was determined that his genes are valuable after all and worth perpetuating for the good of the species. Just last month, a surgeon more accustomed to operating on humans reversed the vasectomy. It's too soon to tell whether the procedure was a success.

Said Don: "We don't know if he's shooting blanks or not."

Oh, let's hope he isn't. Let's hope he's firing off smart bombs.

That might mean the National Zoo could soon be home to a baby Przewalski's horse, which I'm sure is nearly as cute as a baby giant elephant shrew.

To see a video about the National Zoo's birth control procedures, go tohttp://www.washingtonpost.com/johnkelly.