Duke Lemur Center Research - a lemur's perspective

Many people may think of research as being the “downside” to life as a captive animal. But that all depends on the kind of research you do! I can see, yes, if you happen to be a rat in a cage in a biomedical facility, you may be a bit nervous when seeing the scientist in the white coat approaching. But that is not what we do here! None of our projects harm the animals, and in fact, many of the lemurs get very excited (in a good way) when they see the researchers approaching. It means interaction. It usually means food. It never means pain. Let me give you a couple of examples.

Dr. Elizabeth Brannon has been conducting a study of numerical cognition in lemurs for several years now, and it involves the use of a touch screen computer. In a variety of trials that test numerical aptitude, the animals select from a series of photos on the computer screen and are rewarded for correct choices. Rather than bring the animals to the computer, the computer was installed in a mobile lemur-proof cart and it is wheeled into their cages for trials. You cannot imagine the glee in their little lemur eyes when the animals see that cart approaching. Not only are the lemurs happy, but this research has produced some fascinating results, showing that lemurs have transitive reasoning abilities, making it likely that the primate ancestor also had higher cognitive abilities than previously thought.
And let me tell you about Teres, a ring-tailed lemur whose female companion moved to another institution. He was depressed and losing weight. He then started participating in a project by Dr. Matthew O’Neill where oxygen consumption was measured as lemurs walked and ran on a treadmill to get an idea of how much energy was expended as they transitioned their gaits. Some lemurs -as some people- are much more inclined to walk on a treadmill than others. Some, in fact, just sit down and ride it to the back. Because this type of research at the DLC requires voluntary animal participation, the latter lemurs quickly earn a pass. Teres, however, took to the treadmill like a fish to water and not only provided an exceptional amount of data which allows us to better understand lemur energetics, he resumed his normal weight and is now living happily with another female, Cleomenis. It just goes to show that getting out, doing a little research, and getting some exercise can have a positive impact on your life. Even if you are a lemur.
We here at the DLC make every effort to come up with ways to make participation in research a form of animal enrichment; generally all it takes is a little creative thinking, positive animal interaction, and a handful of raisins.

Hear! Hear! Here's to lemur ears!

by Dr. Sarah Zehr
We often make the assumption that the animals around us hear things in the same way we do, yet there are common examples that show that they don’t. The animal known as the human teenager, for example, with its young ears can hear a cell phone ringtone that is at a frequency that most adults, with their aging ears, cannot hear. What, then, does an animal of an entirely different species hear? Marissa Ramsier and Andy Cunningham, of Nate Dominy’s lab at UC Santa Cruz wanted to know. Having already studied the hearing of many other primate species, a trip to the DLC was obviously in order to find out how prosimian primates hear. They made multiple visits and tested the hearing of many of our species, including both nocturnal and diurnal animals. They are still analyzing their data, which should provide an interesting complement to the many vocalization studies that have been conducted over the years.
Of course we care about lemurs in general, but this project also made some fascinating discoveries about some of our individual animals in particular. First, as any of you who have been on the tour path know, the air handling unit by the main building can be quite loud. We were concerned that being near it constantly may have damaged the hearing of animals who live in nearby enclosures. So we tested their hearing. Much to our relief, there were no differences between their hearing and the hearing of other animals of the same species who do not live close to the air unit. It may be that the sound frequency of the equipment, which we find very loud and annoying, is not one that is as prominent in the range of hearing of lemurs.
Although there was no hearing loss in those lemurs, when the hearing of two of our lorises was tested (one slow loris, Lahkshmani, and one pygmy slow loris, Skimmer), they were found to be almost completely deaf! Which explained a lot. Such as why Lahkshmani, who is in our animal training program and is supposed to respond to a whistle, has been terrible at training. She simply couldn’t hear the signal. Knowing the auditory limitations of these two animals will allow us to better care for them. In addition, the fact that the only two animals to show significant hearing loss are lorises may be an indication that there is something interesting about their physiology. Or maybe it’s just coincidence. In any case, the moral of the story is that the research conducted here not only enlightens us about prosimians as a whole, but it can also help us learn about special characteristics of the animals who live at the DLC.

Duke Lemur Center draws researchers from across the nation and around the world

What’s with all the Canadians? Duke Lemur Center seems to have been inundated by researchers from the Great White North this summer. And it can’t just be the weather, as I hear tell it’s quite pleasant there this time of year. Let’s see if I can even name them all: Dr. Kathleen Muldoon, a Canadian researcher based at Dartmouth University, was here studying energy expenditure in our free-ranging ring-tailed lemurs. Dr. Tracy Kivell, a Canadian who has been a postdoctoral researcher here in Duke’s Evolutionary Anthropology department, has been intensively collecting data on aye-aye locomotion all summer before she heads off to a new research position at the Max Plank Institute in Germany. Drs. Sergio and Vivian Pellis came down from the University of Lethbridge in Alberta, Canada (though I should mention that they are Canadians from Australia) to study rough and tumble play in our infants. One of our long-term Canadian researchers, Dr. Marylene Boulet, has been a post doc at Duke studying olfactory communication in ring-tailed lemurs, but she returned to Canada late in the summer to take a research position there. Even the Canadian Discovery Channel was here to film some aye-aye locomotion research for a segment on the show “The Daily Planet”.

And Canada isn’t the only far-off land from which our researchers hail. Masters student Lucy Todd from Roehampton University in London (though she is actually Scottish) is also here recording Sifaka vocalizations, and Dr. Lap Ki Chan made the trip from Hong Kong to study how lorises reach from one substrate to another as they travel.

While we are very proud of our international appeal, let’s not forget our visiting researchers from the good old US of A! Dr. Jandy Hanna from West Virginia School of Medicine has spent much of the summer here studying lemur locomotion, Tess McLoud, a student at Dartmouth, came down to observe ring-tailed lemur infant-male interactions, and Peter Flynn, a high school student from New York who is part of the Intel Mentorship Program, spent all of July collecting data on ring-tailed lemur foraging. Gini Dawkins from Hunter College in New York recently paid a visit to document play behavior in sifakas and red-ruffed lemurs, and Dr. Matt O’Neill, from SUNY Stonybrook, made two trips to the DLC this summer, collaborating with both Dr. Hanna and Dr. Muldoon.

Dr. Roshna Wunderlich, a frequent year-round visitor from James Madison University, made several appearances over the summer to continue her study of sifaka locomotion, Dr. Chris Mercer from Northwestern University will make his third annual visit to do alarm call playback experiments later this month, and Dr. David Hollar, from UNC, will be making the long journey from Chapel Hill to observe and document how ring-tailed lemur groups interact and how they use their environments.

Summertime for some means more downtime, and this is particularly true for students and academics, who tend to have reduced class and teaching responsibilities. Many researchers take this opportunity to travel to the field or to other institutions (such as the DLC) to gather data not accessible to them at home. Which is all well and good but leaves me now, at the end of the summer, in desperate need of a vacation. Perhaps I’ll go to Canada.

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

Greetings from the DLC Research Department

The force with which it's limbs strike the ground are measured as an aye-aye runs across a pressure plate. (Photo by David Haring)

It seems that we in the research department are a bit behind the times in blog world, as I see that the education and conservation departments are already up and running, illuminating their forks of our trifocal mission at the Duke Lemur Center. We will not be left behind, I say! And so, I would like to introduce Research at the Duke Lemur Center. I am often asked why we do research on these animals and what types of research we do. First things first, which means addressing the first question of why we do research on lemurs. How will that help their plight in the wild and their survival in captivity.

The use of captive animals for scientific research ultimately helps conservation efforts of wild populations in a number of ways. It stands to reason that the more we can learn about endangered species, the better our chances of conserving them. By studying the biology of these animals in areas such as behavior, reproduction, morphology, physiology, ontogeny, and genetics in a controlled environment, we can better define species and subspecies status, better quantify their ecological requirements, better understand their interactions with other species, and better determine a conservation plan given the animals and environment we have to work with. In addition, we do a number of research projects that focus on animal husbandry and care so that we can keep our animals happy and healthy here in Durham.

A thermographic image of an aye-aye eating an egg shows temperature variation. Look at his hot ears! (Photo by Andrew Cunningham.)

The Duke Lemur Center houses the largest and most diverse captive prosimian colony in the world, and these animals are used by investigators both at Duke and other national and international academic institutions for both species-specific and comparative research. Only non-invasive research is allowed at our facility, and all projects must be approved by both the DLC Research Committee and the Duke University Institutional Animal Care and Use Committee (IACUC), both of which contain veterinary oversight, before any research can begin. By maintaining these animals at the Duke Lemur Center and allowing experts in the US and international scientific communities to carry out studies of the animals in our colony, we take an important step toward the long-term goal of lemur conservation. Stay tuned for descriptions of the projects we are working on here at the DLC!

A researcher observes a ring-tailed lemur. A ring-tailed lemur observes a researcher. (Photo by David Haring)