Leaping Lemurs

Duke Lemur Center preserves and protects lemurs, unique primates that are the ancient relatives of monkeys, apes and humans. Lemurs evolved in isolation on Madagascar, but are threatened as the island's human population grows. Researchers study behavior, genomics, physiology and conservation biology in order to preserve the existence of lemurs worldwide.

DURHAM — As she opens the gate and begins walking down the trail into a forest at Duke Lemur Center, graduate student Elaine Miller braces herself for her work.

“So let’s see, where could they be today,” she murmurs, scanning the trees and then turning her attention to the ground. “Well, look at that, they’re ready to go.”

She heads further down the trail and walks straight into a pack of ring-tailed lemurs. They have the coloring of a raccoon, without the mask. But then they stand up on their hind legs and begin to bob their heads and weave their bodies. They begin to look like little, furry people with long tails.

Members of the lemur colony begin walking with Miller and then around her, pulling at her bag and chattering. All the while, the huge eyes intently watch and study everything she does.

“Now I just need to concentrate,” she says, smiling. “They are so darn cute and fun to be around.”

In fact, you could say Duke Lemur Center is an island of intense cuteness surrounded by Duke Forest. It is also home to the most diverse colony of lemurs outside of Madagascar. There are about 246 individuals living at the center, which has become a global leader in lemur research. Some of the lemurs live in cages inside the buildings. Many more live in the forest, just as they would in their home in Madagascar. The huge fence, with electrified wires at the top keeps the lemurs from venturing outside the forest.
 
That reputation as a center for lemur research is what brought Miller to Durham from her studies at the University of California at Davis. She’s looking into the concept of social learning; not just in lemurs but also how lemur behavior can be extrapolated to primates. In other words, can primates learn behaviors just by watching each other accomplish a task?

“What I’ve found so far is that they are watching each other to some degree, and if one gets a grape from the box, others will come over to see if they can get a grape,” adds Miller, as she places 10 wooded boxes along the trail.

There are grapes inside each box, which is sealed by a wooden plug. Once the lemur smells the treat, it must figure out how to pop the lid and reach inside to get the grape. The question is, does the lemur learn to open the box by watching others? 

Miller also hopes to understand if more behaviors can be learned in a larger group, because there are more things to watch. Or is it better to learn in a smaller group, where a certain behavior can be more closely observed.

Miller records the entire scene with a video camera and does a play-by-play as we watch about a dozen lemurs move from box to box.

“So you can see Liesel got the grape, which is typical because she is the dominant female,” says Miller, as she points out various lemurs. “So there's Brigita coming over to investigate because she’s been watching Liesel check out the box.”

The entire experiment takes about 15 minutes. Not all of the boxes are opened.

Researchers have discovered that females are dominant in lemur colonies. Males rub the scent glands in their wrist and shoulders to mark the box. That act often opens the box. But then the female grabs the grape out of the box and eats it.

“It’s still learning, because they are watching each other and learning that there are grapes in there and then they copy the behavior,” says Miller. “But it’s difficult to say if they are learning to forage.”

Besides Miller’s work, there are roughly 90 other ongoing research studies at the center.

In addition to the active studies, the center recently made available to the public almost 50 years of data on all of the lemurs that have lived at the center. That includes information on diet, growth rates, genetics, breeding seasons and behavior. The data covers 3600 lemurs. That kind of in-depth data will never be able to be collected again.

“All of the data we’ve collected over the years helps us to manage the current population and make sure it continues into the future,” says Sarah Zehr, a research scientist at the Duke Lemur Center.

Because lemurs are endangered, maintaining a healthy and genetically diverse population is one of the Lemur Center’s primary goals. The last lemurs were taken out of Madagascar in 1993. The Center works with scientists in Madagascar to conserve the wild population there. The lemurs now living at the Center are descendents of the first animals brought over from the island.

“We need to study lemurs not just because they are cute, although for a lot of people that is reason enough,” says Zehr, smiling, as she watches a group of lemurs in a tree. “But one of the reasons people find them so cute and personable is because they are primates, which means lemurs and humans share some evolutionary history. So by studying lemurs we can find out more about human evolution because there are some shared periods in there.”

There are about 75 species of lemurs. Duke Lemur Center cares for 17 of them. Researchers add that in addition to the evolutionary connection with humans, there is another reason lemurs are so fascinating. It’s because they all evolved on one island — Madagascar. And through the years they have evolved to fill dozens and dozens of ecological niches. It’s believed that by studying how lemurs adapt to change, researchers can gain more insights into how people adapt to change.

“Not only can we learn about biological processes through lemurs, but it’s exciting to simply learn about lemurs because they are a fascinating group of biological organisms,” maintains Zehr. “Not only that, lemurs are endangered, so we want to learn about them just for the sake of learning about them. We want to know how they live and what are the differences between the species. And the more we know about that, the better we can conserve them.”


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