My research combines the tools of nutrition, physiology, microbial ecology, and anthropology to answer critical questions in organismal biology. Specifically, I study the gut microbiota and how its responses to shifts in host diet or physiology affect host nutrition and health. Such interactions are likely to affect host fitness and have important  implications for host ecology and evolution. My work addresses these topics in both non-human primates and humans.


Updates - Round 3 Week 7

It is starting to rain again, which has cooled things off significantly. Luckily, most of the rain comes at night though, so we are able to work comfortably in the field still. Cooler weather means the monkeys are more active. It’s a nice change, but this week Balam was very active and tended go into the middle of tall trees with dense leaves almost every day. There was also at least one howling encounter with another group every day. Data collection was a challenge.

 On top of that, the Balam males were very difficult to tell apart. Although they have some distinguishing characteristics, they are subtle and hard to see if the monkeys are moving quickly or if the light is wrong. Usually we use botflies to tell them apart more easily. Botflies are flies whose larvae grow under the skin of a mammalian host, in this case, the monkeys. When a monkey has a botfly, it develops a very visible lump wherever the botfly is—face, neck, chest, back, etc. Because different individuals have botflies in different places, this makes it easy for us to quickly identify the monkeys once we know where each one has a botfly. However, the botflies only last for about a month, after which the fly emerges and the lump disappears; we are constantly on the lookout for new ones. One of the Balam males has had a botfly on his right collarbone for the past three weeks, but this week it was almost gone. The other male has no botflies. While this is great for the monkeys, it made it very difficult for us to quickly distinguish the males from one another. We were able to do it using the faded botfly, a faint scar, and facial characteristics, but several times we had to follow our focal individual around after the focal had ended to verify the identity. Luckily, the females and juveniles are easy to tell apart using permanent characteristics so our frustration was limited.

Aside from the monkeys, we saw a coati this week. This is the first time I've seen this raccoon-like animal in Palenque National Park! We also saw an encounter between a small snake and a big tarantula. I didn't get close enough to see what the end result was, but when I looked at the pictures I took, it looks like the snake is belly-up.

The end result of snake v. tarantula.

 Teresa and Luz resting together.


Updates - Round 3 Week 6

The heat continues! Melanie's interest in Isa's baby also continues. Melanie constantly follows Isa around and handles her baby whenever she gets the chance. There have been a couple more instances of aggression between the females, too. Although social behavior is not my focus, it's very interesting to watch all of these interactions. They remind me how important inter-individual relationships are among primates.

As I've mentioned several times, the heat is affecting the monkeys' behavior. We've had a few days where the monkeys rested for eight hours! This makes collecting behavioral data easy since they are not moving very much, but it makes collecting fecal material difficult. Instead of defecating several times each day, the monkeys defecate only once around 4pm. Howler monkeys in a single group tend to defecate all at one time. Now though, because they are all resting in a pile, they also all defecate in the same place. This makes matching samples to monkeys tricky. We get all of the samples coming at us at one time in one place, and we only have one chance at them per day. Sample collection is hectic to say the least. Still, we're getting it done. We have not missed a single sample, and we were able to collect from the 5-month-old infant again this week!

This week we also ran into a large fer-de-lance (or nauyaca). It was at least 2m long and curled up in a ruin. It was beautiful. Its coloring was quite different from the small one we found a few weeks ago though. I believe this week's was a true fer-de-lance. The small one is likely a different species, but I'll have to check with a herpetologist.

The hummingbird nest we found (unharmed) near the nauyaca this week was also beautiful. It's amazing how small they are! Slightly bigger than a golf ball...with mint-sized eggs. It was in a tree about 1.5m tall. I'm always amazed at how fragile they seem and at how precariously placed they are. I wonder how often they are damaged or destroyed.

A nauyaca resting in some ruins under a tree where the monkeys were resting.

 A hummingbird nest on top of the ruins where the nauyaca was curled up.


Updates - Round 3 Week 5

There's another new infant! This time it's in our other focal group, Balam. On our last day with Balam, two weeks ago, we couldn't find Luz, and when we found her this week, she had a baby! Just like in the Motiepa group, the other female in the Balam group kept taking the infant from Luz. It's a little different in this case though because Teresa does not have her own young one, and we haven't witnessed any aggression over it yet.

The other exciting news is that we were able to collect from two more of our outside groups this week. That means that only one remains, and we still have five weeks. Although we're not completely finished with the extra groups, being so far along this early on takes a lot of the stress away.

Aside from these two developments, the rest of the week was pretty routine. We did spot a new kind of snake (for us) on Tuesday though. It was only a couple of centimeters in diameter and maybe a meter long, but it was a beautiful green/blue/turquoise color with a red/brown head. I've never seen it before, and I haven't been able to identify it yet, but it was quite striking. Unfortunately, the encounter was too quick for a photo so I'll have to rely on my memory as I continue to search for it in books.

Teresa inspects Luz's new infant.




Updates - Round 3 Week 4

Week 4 was full of little surprises. The most exciting was that we were able to collect a fecal sample from Melanie’s “infant,” who is now about 5 months old. Samples from monkeys that young are tiny and tend to fall without warning so they are very hard to get. Furthermore, the unique developmental stage and diet (milk and solid food) of this juvenile suggest there may be interesting microbial differences when I compare this sample to the others. The fact that we were able to get it made me happy for most of the week.

Most of the other surprises this week involved Isa’s infant, who is only about three weeks old. The first series of situations came about because Melanie kept taking the baby from Isa. Most times Isa didn’t seem to mind, but one time she clearly wanted him back. The only problem was that Melanie didn’t want to give him back. She grimaced and swatted at Isa, who acted submissive and had to wait patiently until Melanie finally allowed Isa to take him. Intra-group aggression is fairly rare in howlers, so to see Melanie lash out was unexpected, especially when she is not the mother. Brianna and I were on opposite sides of the tree watching different monkeys when it happened, but we both saw it and gasped at the same time. Obviously, Melanie has a strong interest in this infant, but we’re still not sure why.

Another time, Maia, the infant’s one-year-old sister somehow ended up with him on her back. It was amazing to see how big such a tiny monkey looked on an only slightly-bigger monkey. The whole situation was funny in a sweet kind of way until Maia decided she wanted to play. All of sudden, she was hanging from her tail with her brother clinging onto her for dear life while she tried to undo his grasp one limb at a time. We all held our breaths until Isa came to the rescue and took him back. To be honest, I was impressed that Maia could hold both of them up for so long using only her tail. He looked heavy!

Maia with her 3-week-old brother hanging on for dear life.

Isa comes to the rescue!


Everything else was fairly routine this week. The heat index was at 43C (109 F). The monkeys slept for four hours each day. We found some more ticks. There were several intergroup interactions in opposing Poulsenia trees. And, of course, we had to walk part-way home yesterday because no ‘colectivos’ showed up outside the ruins and the forest when we were done for the day. Also, on a slightly unrelated note, I went on a run this morning, and there are trees with beautiful pink flowers in bloom everywhere along the highway. It made me smile.


Updates - Round 3 Week 3

Things got a little crazy with the beginning of May. Our focal group this week decided to stay out of view during many of the hours we were following them. We got data, but we had to work hard for it. At the same time, a neighboring group that we want fecal samples from for this season appeared and foiled us on two separate occasions. We decided to try to get samples as long as we knew where the group was, but the first time they appeared, they did not defecate. The second day, they all switched spots right before they defecated and did it from high up in a tree so that not a single sample fell to the ground in one piece.

To make up for our lost opportunity with the extra groups, Brianna and I split up to collect from two other extra groups on Saturday with the help of colleagues. Both of these forays were successful , and we now have half of our extra groups sampled in addition to the focal data we have been collecting.

The dry season means ticks, and this week I had my fair share of ticks. I found ten on me in the field in one day, which is more than the total number I have found on me in past years. Luckily, most of them were still crawling around looking for a place to dig in when I saw them. I only found one or two that had actually bitten me already.

5 de mayo was this week, and although it was quiet in Palenque, just the thought of a holiday put me in a good mood. This was a good thing though because it kept me alert, and I was able to spot what I consider my “5 de mayo present from the forest” quickly.  As we were marching out of the forest for the day, I spotted a ‘nauyaca,’ or fer-de-lance, in the center of the path. It was very small (maybe 0.5 meters), and it was coiled up and seemed to almost not notice us. These snakes are very venomous, and supposedly common in this forest, but I’ve seen very few during my time here. I prefer that for our safety, but snakes fascinate me. We stood and took pictures of this one from a safe distance until I was able to tear myself away. Unfortunately, this made us a little late in getting out of the forest, and there were no ‘colectivos’ (public transportation vans) to give us a ride when we emerged from the forest. We had a long walk home, but to me it was worth seeing the nauyaca.

Nauyaca or fer-de-lance!


 Colorful fecal samples from one of our extra groups in a forest fragment.