Scientists at the Oregon Zoo have tried nearly everything to get their endangered pygmy rabbits to breed. They’ve constructed really nice cages and placed the females in them with males the scientists chose based on their genetic variation.
But no dice. They refused to breed in captivity at anything like the rate they do in the wild — just like most of the endangered species that scientists have been trying to breed in zoos around the world.
Most of the pygmy's Eastern Washington habitat has been taken by agriculture, so the species’ only chance for survival is captive breeding.
Meghan Martin, a researcher at the Zoo, had an idea: maybe rabbits are more like people than we think; maybe they want to choose their own mate, not the one chosen by a scientist for its genetic qualities.
So she and the zoo’s Director of Conservation David Shepherdson conducted an experiment that just might change the way zoos and breeding operations around the world do business.
Martin placed a female pygmy in a cage surrounded by three abutting cages, each containing a male pygmy rabbit.
In what zoo officials are referring to as a “speed-dating program,” that actually lasted a few weeks, the female was free to choose which of the three males she wanted to be placed in her cage.
When the female started rubbing heads through the fencing with one particular male and running parallel to him along the barrier, they figured she had made her choice.
The scientists let her have alone-time in the cage with the chosen mate, but for the sake of scientific research, they also paired other females with males they hadn’t chosen, and other males with other females who had not spent a few weeks as caged neighbors.
About a month later, Martin and her colleagues checked to see how the various pairs had done. Not surprisingly, they discovered that when the females were allowed to mate with males they had chosen, they were more likely to produce offspring than in any other type of situation.
They also found that mating the female with a neighbor rabbit she had not chosen worked better than when she was placed in a cage with a stranger.
Not only that, but females paired with preferred males and neighbors had larger litters than they did with strangers. And even more interesting is what the scientists discovered a year later: twenty kits born to couples who had spent a week as neighbors (and in some cases chosen each other) survived. Only two kits born to rabbits paired as strangers survived.
All of which says that, maybe, zoos have been taking the wrong approach all along in deciding which animals to match up for mating. Making genetic diversity the first priority may have been missing something the rabbits already knew how to handle.
“In the wild, every one of these animals has mate choice,” Martin says. “The way we were going was just genetic based. It baffled me. You wouldn’t expect two humans thrown into a room together to have a baby. Why do we expect that from endangered species?”
Shepherdson says reproductive biology for endangered species is a relatively new and little-studied piece of captive breeding programs. In the lab, he says, female mice that were mated with preferred males have produced better offspring than when they were paired with strangers.
The Oregon Zoo experiment has simply taken the idea one step out of the lab and into the field with wild animals.
Martin says, that different species have different mating behaviors that scientists need to uncover. She’s certain that letting animals choose their mates is an important first step.
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