Hollie Colahan's second-floor office at the Denver Zoo features a standard magnetic whiteboard. But its content is far from standard: This is the Magnetic Whiteboard of Lion Sex.
That's not what Colahan calls it, of course. To her, the board's blue dots (boy lions) and red dots (girl lions) represent serious business. As the Species Survival Plan coordinator for African lions in a hundred zoos across the country, Colahan oversees the process of pairing genetically diverse blue dots and red dots to make white dots, or lion cubs.
"If there's a B in the box, there's a breeding recommendation," Colahan says, pointing to a neat grid in which each box signifies a different zoo. The boxes are filled with dots to indicate lions in residence; in some of the boxes, Colahan has scribbled notes such as "making exhibit modifications" or "can't take more cats right now." It may not look super-sexy, but the Association of Zoos and Aquariums believes such data is necessary if American zoos are to maintain a healthy and sustainable (read: not inbred) population of captive African lions. And that's important, because African lions are disappearing from the wild.
"It's not just a matter of 'We want lion cubs because they're cute,'" explains Colahan, whose official title at the zoo is Curator of Large Mammals. The bigger goal, she says, is to make sure that the entire zoo population is viable one hundred years from now. And that won't happen if the animals are allowed to get all Flowers in the Attic and start lusting after their siblings because they've been locked in this attic together for years. So great pains are taken to transport animals across the country — sometimes in the cargo bays of commercial flights! — to breed with other animals that aren't their brothers or sisters.
"We prioritize breeding the animals that have the fewest relatives in the population," Colahan notes. "We use this analogy [of] online dating and matching animals up — and those are the pieces we're looking at: Where are they, genetically, in the population?"
In other words, Colahan and her ilk don't care which lion has the fluffiest mane or which are social drinkers and non-smokers except if they're drinking. What makes an animal truly valuable in the eyes of zoo matchmakers is if it's unrelated to any other captive animal.
According to Candice Dorsey, the AZA's director of animal programs, there are Species Survival Plans for more than 500 animals, ranging from tarantulas to tigers. Each of those species also has a coordinator who volunteers (coordinators don't get paid for their work) to keep a "stud book" that lists all of the eligible — and ineligible — males and females. Several things could make an animal ineligible: if it's related to too many other animals or is too old to breed, for example, or if it's so ornery that it would rather fight than fornicate.
Colahan and her AZA colleagues develop a Breeding and Transfer Plan each year that lays out how many baby lions should be born to offset the number of older lions that are expected to die. "We create these life tables that are like what actuarial scientists use for life-insurance companies," Colahan says. The baby-lion goal "is sort of a moving target, depending on what's going on with the population."
Once Colahan has that number, she begins coordinating the babymaking. She works with zookeepers around the country to figure out which lions should breed with which lionesses. In addition to an animal's genes, they consider several other factors, such as personality and age. It's easier to make the first introduction between a male and a female when they're young, she explains; by the time lions are older, they're more set in their ways.
So how do you tell if two lions will get along? It starts with that introduction. "We bring them in and let them see each other first," Colahan explains. "And then, typically, they can get close to each other with a barrier in between, like a fence, and we can gauge how they're reacting. Do they seem like they really want to be together? Do they seem like they want to eat each other?.... There's usually a lot of noise and a lot of chasing each other around."
Although some big cats, like leopards, have been known to kill each other when introduced, that's rare with lions, Colahan notes, because lions are social by nature. "It's fairly unusual, but it does happen," she admits. "They're large predators, and they're certainly capable of causing serious injuries. That's what we look at when we do introductions: Is this just swatting each other on the nose and sorting out who's boss? Or is this really serious, and these guys don't want to spend any time together?"