Research at the Lemur Center - a matter of taste

Photos by David Haring
Lemurs enjoy their choice of beverages!

People often ask what kinds of research we do. We have many projects in progress at any one time, and I will periodically introduce new and ongoing studies and post updates so that folks can get a sense of what we are learning from these animals and how. Let's start with a simple yet important study that one of our Primate Technicians, Erin Nemecek, has just undertaken to identify taste preferences in our different lemur species. As you might imagine, our lemurs get sick from time to time with anything from parasites to an infected wound, and they need to take medicine in order to heal properly. Like most of us, the generally don't like medicine. And, not surprisingly, there is really no information in the literature about lemur taste preferences. So we if we can figure out a flavoring to add to the medicine so that the lemurs will take it readily, that means that they don't have to be caught to be medicated, which makes them happy. And it also means that we can ensure they consume all the proper dose so they get better - which makes us happy!

"We are supposed to drink this, right?"

What is a lemur's favorite flavor? Groovy Grape? Mandarin Orange? Peaches n' Cream? Mom's Banana Bread? Erin obtained a number of liquid flavors from the Flavor Rx Institute (which was kind enough to donate the flavors!), including both sugar and salt solutions that can be used as the foundation for any of the flavors. She is going to run tests on different animals to see which of the flavors the different species prefer so that they can be more easily medicated when necessary. We are starting with animals representing five genera: Lemur (Lemur catta, the ring-tailed lemur), Propothecus (Propithecus coquereli, Coquerel's Sifaka), Varecia (Varecia variegate rubra, the red-ruffed lemur), Daubentonia (Daubentonia madagascariensis, the aye-aye), and the Eulemur (Eulemur mongoz, the Mongoose lemur.) Each study animal will be offered 3 ml of the flavoring in a disposable Dixie cup, and the amount consumed after one minute will be measured. Each animal will be offered a single flavor each day for the three consecutive days and their preferences inferred by how much of the solution they consume.

Mongoose lemurs use their little lemur hands!

The first step is to start working out the project parameters for the study, and so we will do a few tests with non-subject animals to figure out the best way to conduct the trials. Erin and I started with Mongoose lemurs on 12/2/2008 and used two pair: Felipe and Moheli, and Pedro and Maddie. Instead of the flavors that we will use in the later trials, we just started with juice that we know they like to get an idea of how things will go. Then, once we see that our test system is working, we'll present the actual flavors to test-subject animals. David (Research Technician) made some wooden cup holders with a stable base that a Dixie cup will fit into, and the idea was to just put the solution into the cup, put the cup into the base, and set it on the floor of the cage. Of course, the mongoose lemurs like to use their little lemur hands, and Felipe managed to take the cup right out of the base. Then Moheli took it away from him and dropped it on the ground, making it impossible to measure how much was consumed. We discovered that if we cut the cups down to right below the lip of the base, they can't get them out and instead drink from the cups, so it looks like that's what we'll do.

Please, may I have some more?

Erin and I continued testing on the rest of the species, with Varecia (Galaxy and Comet) and Propithecus (Lucius and Irene) and Daubentonia (Lucrezia) and Lemur (Nemo and Agathon.) It seems that every lemur is different. Who knew? It turns out that Em, Pvc, and Dm could and did remove the cup from the holder, but interestingly - all in different ways. Mongoose lemurs use their hands, Sifaka just smash their faces so far down into the cup that when they lift their heads, the cup pops out and they then run off with it, and the aye-ayes use their teeth to remove the cup before scampering away. Trimming the cups down was effective for the mongoose lemurs, but not good enough for the props. Taping the cup to the bottom of the holder worked for the props, but was not good enough for the aye-ayes. So David is going to make a special base for the aye-ayes, and then we can start the project in earnest. The Varecia and the Lemur catta didn't mess with the equipment at all. They just smiled and said, "Ahhhh! Juice."

blog by Sarah Zehr

Lemur Learning: Training Enriches Exam Time at Duke

Life is fairly quiet at the Duke Lemur Center at this time of year. The Duke students, who would normally be conducting observations or doing non-invasive research, are preparing for or taking exams. The more than 30 Duke affiliated researchers (All our research is non-invasive) are preparing or grading exams. So from the lemurs' point of view, there are not only fewer people, there is less activity than usual.

Now, lemurs and their fellow prosimian primates, lorises and galagos, are intelligent. In fact, research being done here is showing that they are more intelligent and more socially oriented than was previously understood. That means they can get bored. So, 365 days of the year our dedicated Primate Technicians make certain that their lemurs' lives are interesting.

One way the technicians enrich the lemurs' lives is through a training program. First, all the techs completed a course by Meg Dye in animal training based on the science of operant conditioning . They use positive reinforcement to train the lemurs to allow themselves to be touched by the trainer, to sit on a scale, to enter a kennel, to move to a certain certain spot - a set of behaviors that just seem like play to the lemurs, but can serve a purpose when needed.

For instance, Pia, a Coquerel's sifaka, is very pregnant. So her technician, Sam, is training Pia to allow Sam to touch her belly. That way Pia will be less stressed and more comfortable after her infant has arrived and Sam needs to approach Pia and lift the infant from her stomach to be weighed. Sam will give a familiar command and Pia will know that it is safe for Sam to touch her belly and that she will receive a tasty treat.

Each appropriate response from the lemurs merits a treat, like a raisin or a nut - depending on what is a treat to that animal. The techs wear a special belt that has a treat pouch attached. When the animal responds appropriately, the techs click a clicker. That sound tells the lemurs that a treat is coming. That way if there needs to be a brief wait between the behavior and the reward, the lemur still knows it's coming. I think of it as that space between the timer dinging on my stove at home and a warm cookie making into its way into my mouth.

The techs also make sure that they end each session with behaviors that are sure to get a positive response from the animal. That always brings the Jackpot - a small handful of treats.

As I watched the training, it certainly looked like both trainers and lemurs were happily engaged. I know as Sarah and David were training sifaka in one cage, the ringed-tails in the next cage were getting as close to the sifaka cage as they could, jumping excitedly and making a sound that Sarah described as a whine. It was easy to picture a young child watching another play with a special adult and calling, "My turn! My turn!"

Lemurs and a Thanksgiving Feast

Food! Glorious food! I personally think that may be the lemur theme song. Of course, lemurs don't know about Thanksgiving, but the Duke Lemur Center Primate Technicians do. They care for the lemurs and their fellow prosimian primates 365 days of the year. The techs work hard to see that every day is safe, comfortable, and interesting for the precious animals in their care. So the techs have planned some special treats for Thanksgiving.

Pumpkin flavored with cinnamon, sweet potatoes, corn, apples, grapes, bananas, grubs, meal worms - - - Yum! Of course, the pumpkin will be spread on branches so it can be delicately licked off; the sweet potatoes may be hidden in empty cans, and the corn may dangle from a string tied to the enclosure wire, but from a lemur point of view, that counts as "presentation." We call it enrichment for the animals. Hunting, climbing, sniffing out lunch in odd places makes life more interesting. Perhaps it sets off some genetic memory of lemur life on Madagascar.

In the picture above, Hesperus, a black lemur, is enjoying a cantalope that he planted himself - in that most natural of ways that animals plant seeds of fruit they have previously eaten. When the seeds sprouted, the techs took care of the plant until the melon was ready to harvest, and Hesperus could enjoy the fruits of his labor.

I did want to mention, again, that these delightful pictures are taken by David Haring, Duke Lemur Center's Registrar and Photographer.