Nov 2018 updates


Nov 7-9 at Ohio State University: Modeling and Analysis of Dynamic Social Networks

(I’m giving the first talk at 1pm)

Nov 8 Seminar: “Wireless tracking sensor network give novel insights into the (social) life of bats” by Simon Ripperger. (1:00–2:00pm, Room 110, Orton Hall, The Ohio State University). Simon is visiting my lab this fall and joining us this spring to track wild vampire bat social networks (and vampire bat-cattle networks).

Some recent and relevant papers:

The ecology of movement and behaviour: a saturated tripartite network for describing animal contacts. “we relate individual movement trajectories to contact networks through a tripartite network model of individual, space, and time nodes”

Kin selection and allocare in sperm whales. “babysitting rates were correlated with relatedness (rs = 0.4, P < 0.05), and allonurses were, on average, closer maternal relatives of the calves they nursed than were available females who were not allonurses (Δr = 0.14, P = 0.054).”

The “tolerant chimpanzee”—towards the costs and benefits of sociality in female bonobos. “our results support the hypothesis that predicts that females trade off feeding opportunities for safety against male aggression”

Social bonds facilitate cooperative resource sharing in wild chimpanzees.”The strongest predictor of sharing across food types was the presence of enduring and mutually preferred grooming partners, more than harassment, direct signalling, or trade. Moreover, urinary oxytocin levels were higher after the sharing of both individually and jointly acquired resources compared with controls.”

Group and kin recognition via olfactory cues in chimpanzees . “Chimpanzees sniffed … significantly longer at odours from outgroup individuals than those from group members… the duration of sniffing was positively correlated with relatedness”

More than kin: subordinates foster strong bonds with relatives and potential mates in a social bird (the cooperatively breeding purple-crowned fairy-wren).  “subordinates formed equally strong social bonds with kin and potential mates (unrelated opposite-sex individuals) while they formed antagonistic relationships with reproductive competitors that offered no kin-selected or mating benefits (unrelated same-sex individuals)”

Resource Ephemerality Drives Social Foraging in Bats. “Miniature GPS-microphone tags allow monitoring wild bats’ movement and interactions. Bats foraging on ephemeral resources move in groups in variable movement patterns. Bats foraging on predictable resources move alone and in fixed movement patterns.”

By-product group benefits of non-kin resource-sharing in vampire “Our study focuses on the contrast in the group estimates between sharing and non-sharing populations. For constant ecological resources, sharing behaviour can increase the sustainable population size, increase the total resource stored in the population, and reduce the average resource required per individual, compared to a non-sharing population.” I do not agree that this group-based modeling approach makes the correct assumptions.

Quantitative Matching of Clutch Size in Reciprocating Hermaphroditic Worms. “worms reciprocate eggs conditionally to the partner’s behavior and adjust the quality of cooperation according to that of their partners”

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New grad student: Imran Razik

Imran PhotoI’ve always been incredibly curious about the natural world and how it works, especially the animal kingdom. As a kid I would spend hours peeking under rocks, watching documentaries, and reading through wildlife encyclopedias. My entire childhood was focused around biological exploration, be it outside or in a book, so when I finally found out what “zoology” was in fifth grade, it immediately resonated with me, and it was then that I decided to become a zoologist. Although it was a vague plan at the time, my motivation only strengthened as I got older, ultimately leading me to apply for my bachelor’s degree in zoology at SUNY Oswego.

At university, I immediately jumped into a two-year long laboratory position as research assistant to Dr. Julien Bachelier, an evolutionary biologist and plant systematist. Following this, I began an animal ecology research assistantship to diversify my skillset in the field, first aiding in a study on the behavioral responses of white-footed mice and Northern short-tailed shrews to predation threat. The next year, I collaborated on a project which led to my first publication on same-sex courtship behaviors in fruit flies. Shortly thereafter, I travelled to Costa Rica with my research advisor, Dr. Maria Sagot, to help study the importance of group vocal behavior on roost-finding efficiency in Spix’s disc-winged bat. After Costa Rica, I worked for two months at the Bronx Zoo in New York City, and while it was fun, it helped me realize just how much I valued the intellectual rigor of research. So, when I returned to university, I was confident in my scientific and professional goals. I became a teaching assistant for a mammalogy course, which I found very rewarding, and I further conducted an independent undergraduate thesis on seasonal changes in beaver activity and the impact of beaver presence on diversity at an artificial pond ecosystem.

Understanding animal behavior at its core has always been my greatest passion, so I’m not surprised to find myself excitedly starting my PhD in Evolution, Ecology, and Organismal Biology. I also look forward to working with Dr. Gerry Carter, and my plan is to follow up on his most recent work and look more closely at the formation and stability of vampire bat social bonds. Overall, I hope I can make significant contributions to the fields of behavioral ecology and biology, and one day pay it forward to the next generation of young curious naturalists who find themselves endlessly reading, watching documentaries, or peeking under rocks.

Imran Razik is a recipient of the Ohio State University Graduate Enrichment Fellowship. he is conducting experiments in Panama on whether oxytocin explains individual variation in how vampire bats respond to new group members.

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New grad student: Bridget Brown

brown.6531My entire childhood up until I graduated high school, I was confident that I would be working with animals as a veterinarian. However, after volunteering at small animal clinics for two years, I realized that I no longer desired to become a veterinarian. My interests changed to wanting to invest time in conserving wildlife. I was enthralled by conservation courses in college and research that used biology to aid in protecting species. My first internship to try to gain experience in the field led me to a research station called Para la Tierra in Paraguay. My independent proposal was looking into the movement of Rococo Toads. The study was to look at the homing ranges of these species to determine the effectiveness of pest removal.

My experience in Paraguay was so impactful that I wanted to continue fieldwork on similar projects. I applied for an internship with the Division of Wildlife through Ohio State University. For three months, I learned how to radio-track and mist-net bats while also conducting vegetation surveys. The goal of the research was to look at roost selection of eastern red bats in undisturbed and disturbed habitat to determine better management techniques for a new property that the Division of Wildlife had obtained.

This internship eventually led into a full-time position where I was also able to manage other projects, such as a mobile acoustic study looking at the change in activity and species composition after white-nose syndrome was discovered in Ohio. Working with state government taught me about the barriers in trying to conserve bats. The Division always tries to create policies and standards using the most recent research, but there is surprisingly little information on bat migration patterns, their roosting habits, or even their diets to help guide their protection. In addition, the majority of land in the state was privately owned, and many residents held negative stigmas about bats and did not understand their importance. My frustration at the lack of data to aid in conservation along with my wonderment at the behavior of bats led me to applying to obtain a Masters of Science at Ohio State University.

My goal is to incorporate the study of bat behavior with conservation. My thesis project will involve determining the sensory factors that are involved when a bat chooses a roost. Using experimental roost boxes, we hope to determine if olfactory cues, acoustic cues, or a combination of the two are significant in the choice of roosts by temperate and tropical bats. Obtaining information about the sensory cues involved in roost selection could aid in attracting bats to artificial roosts for conservation purposes in the future.

This summer, Bridget plans to conduct experiments in Ohio and Panama on olfactory cues for roost selection. In the meantime, she’s been learning about statistical analyses with R.

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Updates: June 2018

A few updates:

  • I’m delighted to announce my first three graduate students at Ohio State University: Bridget Brown, Theresa Chen, and Imran Razik. Read more about them here.  Theresa and Imran have both won competitive fellowships from the university.
  • We published a study showing that younger vampire bats are more exploratory than adults. They are far more likely to check out and interact with novel objects.
  • PhD student at UT Austin, Basti Stockmaier, published the first part of his work on the effects of an immune challenge on vampire bat social grooming. In this paper, Basti shows that vampire bats respond with physiological and behavioral responses to LPS (lipopolysaccharide) injections. We observed a decrease in social grooming, even when we forced the bats into close proximity with just one or three others in small independent cages. We are now writing the second part of the study, where we looked at the same effects on grooming and food sharing under less controlled conditions, where the bats are housed all together in a flight cage and proximity between the bats can vary.
  • Past intern Julia Vrtilek published her study testing vampire bats escaping from a maze in the presence or absence of demonstrators that already know how to get out. The underlying motivation for this study was trying to think of a simple way to study social learning in vampire bats that did not involve food or require fasting the bats, and where the bats could be tested quickly and repeatedly. In this test, the bats are rewarded not with food but with being reunited with their group.
  • We are almost done with data analysis for the main experiments on Panama– on (1) the development of new food-sharing relationships between strangers and (2) tracking the associations of the previously captive bats, after their release into the wild using proximity loggers. More on that soon!


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Fieldwork: Lamanai, Belize

This week I’ve been working with a team of bat researchers in Lamanai, Belize (an archaeological site of the ruins of a Mayan city).  We are collecting data for a study on the effects of sickness behavior on social associations in wild vampire bats. Last year, PhD student Sebastian “Basti” Stockmaier and I conducted two projects on how social behavior is affected by lipopolysaccharide (LPS)—a bacterial endotoxin that challenges the immune system and induces sickness behavior. LPS can cause symptoms of sickness such as fever and lethargy, but the effects are temporary and the animal makes a full recovery because there is no actual pathogen. The effect of LPS on social networks was first studied by Patricia Lopes. She injected mice with LPS or saline and tracked their nest-sharing associations. Mice that were injected with LPS were less socially connected to others. This work is important because it shows that sickness behavior can reshape social networks and therefore change how a pathogen might spread.

Basti and I conducted three studies on the effects of LPS on vampire bat social behavior. In one study, we injected vampire bats with either saline (control) or LPS then isolated them and counted how many contact calls they produced. In another study, we individually fasted bats in a large captive colony housed in a flight cage, injected them with LPS or saline, and then looked at whether they received more or less food from their group-mates. We also looked at whether the sick-feeling bats gave or received more social grooming. Finally, to experimentally remove the effect of association, we tested the effects of LPS effects on grooming given and received when bats were forced into constant association by keeping them with one or 3 others in close proximity. We did this test because sickness behavior might have an effect on both social associations (being in the same place at the same time) and social interactions (e.g. mating, fighting, grooming, food sharing) and although people often use associations as a proxy for interactions, they are not the same thing. These studies were all done while I was in Rachel Page’s Lab at the Smithsonian Tropical Research Institute in Panama, and they should be published this year and next.

Next, I thought it would be good to complement these captive studies by looking at effects of LPS on vampire bats in the wild. So Simon Ripperger, my wife Michelle Nowak, and I joined a field trip that Brock Fenton and Nancy Simmons take to Lamanai every year.  Simon Ripperger is the only person who could track social associations between more than 30 vampire bats simultaneously. We also teamed up with disease ecologist Daniel Becker who has been banding and monitoring the physiology of the vampire bats at Lamanai the last few years.

Brock knew about a large hollow tree full of insect-eating Saccopteryx bilineata, insect and nectar-feeding Glossophaga soricina, and our target: the blood-feeding Desmodus rotundus. To catch the emerging bats, we strung up mist-nets using a jerry-rigged pulley system. Saccopteryx emerged at dusk, followed by the Glossophaga. Next, we began to capture males going in and out of the tree (see images below taken on previous years at the same roost exit by Brock Fenton).


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Vampire bat exiting the roost (above and below). Photos by Brock Fenton.

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After a slow period, we began to catch females exiting around 2 am. By the end of the night we had captured more than 40 females and even more males, and we stopped because we ran out of bags and had more than we needed (image below).


cloth bags each holding a vampire bat

We released 34 female vampire bats with proximity loggers, half being injected with LPS and the other half with saline. Daniel Becker banded both males and females and took blood and hair samples for his long-term studies.

Using Simon’s proximity logger system, we could remotely download encounters between bats over the next 4 nights, without having to disturb or recapture them. The loggers document the duration and distance estimates of encounters among up to 60 individuals at distances from touching to 10 meters. My prediction is that the immune-challenged bats will have fewer encounters with others because they will be less active, and that the effects on association will not be as dramatic as what can be seen when observing the actual interactions.

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Vampire bat with 1.5 g proximity sensor (above and below). Photos by Brock Fenton.

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Some pics from Panama and Germany

I’m finally seeing bats flying around here at dusk in Germany, and for the first time I’m missing Panama a bit. But it’s not that I don’t like Panama, I just love where I am now! I’ve been trying to make the most of my time here, and that’s my excuse for not writing a blogpost in awhile. More research results to report soon. In the meantime, here are some pretty pictures.

The last two years, I was in Rachel Page’s Lab at the Smithsonian Tropical Research Institute in Gamboa, a small town on the middle of the Panama Canal, at the center of the skinniest bit of the isthmus connecting North and South America. In the Canal Zone in Panama, you can drive from the Atlantic to the Pacific Ocean in one hour.


There were free-tailed bats living in the broken air-conditioning unit in our bedroom, and tent-making bats above our back door. On some days, the Gamboa titi monkeys (Geoffrey’s Tamarins) would stop by and we could feed them bananas. Samuel Diaz Munoz did his PhD on this population studying their fascinating system of cooperative breeding. A female mates with two or more males, and the males cooperate in caring for the young and carry them everywhere on their back.

There was a new species of free-tailed bat discovered in Gamboa. Here’s a picture we took of species of bat in Gamboa

This November I came to the Max Planck Institute for Ornithology to join Damien Farine’s lab in Möggingen, which is a tiny adorable village on the outskirts of Radolfzell, which is a lovely small town near Konstanz, which is beautiful small college town, which is next to the very scenic Lake Konstanz, which is on the German border with Switzerland. That means we can see some of the Alps!

Möggingen is really quaint and bucolic. This is the very modern main institute building. Inside there’s a two-story indoor bird cage.

Most of the Department of Collective Behavior (including the groups of Iain Couzin and Alex Jordan) are in Konstanz. But Martin Wikelski, Dina Dechmann, Kamran Safi, and Lucy Aplin are all people whose work I know about that are based here, just down the road. The research being done here is awe-inspiring:

I work in this building straight out of Grimm’s Fairy Tales, called ‘the mill’.




the backside of the building facing the garden


homes for mason bees in the garden

We are right next to a small pond and a castle. (There ain’t no medieval castles where I’m from).


Living here and working in Damien’s lab has been fantastic. Last week, our lab had a get-together to say goodbye to MSc student James and celebrate him defending his Masters and being accepted to doing a PhD.



James is pretty stoked.


The star of the lab is Lucy and Damien’s cute parrot named “Gili”







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Tracking our vampire bats after they are released into the wild

After almost 2 years of cooperation experiments in captivity, we are now attempting to monitor the social relationships of our vampire bats as we release them back into the wild. We are hoping to track bat-bat and bat-cow encounters. To do this, we are attaching networked proximity sensors to 23 previously captive and captive-born bats with known social relationships and 27 new wild-caught female bats. We are then placing the cattle “prey” in a new location they have never been before. A grid of tracking stations will hopefully allow us to reconstruct their flight paths as they approach the cattle. We are also sampling their microbiomes to look at the microbiome similarity between bats within the colony, and at changes with the move from captivity to the wild.

This collaboration involves an international team of researchers including a very generous landowner, several local cowboys, two postdoc biologists (Simon Ripperger and Gerry Carter), two engineering students developing the software and hardware (Björn Cassens and Niklas Duda), several more engineers back in Germany, two field biologists helping with fieldwork and bat wrangling (Jineth Berrío-Martínez and Darija Josic), two PhD students doing the microbiome sequencing (Karthik Yarlagadda and Aura Raulo), and two principle investigators based in Panama and Germany (Rachel Page and Frieder Mayer).

The captive-born bats have apparently so far survived the transition to life in the wild (it’s their sixth day), but the tropical climate is putting the new technology to a difficult challenge. How well will the captive-born bats be integrated into the group? Will relationships formed in captivity be maintained in the wild? Do food-sharing bats also forage together? Hopefully, we will have some answers soon.


Here’s the post describing when we captured the bats from the roost (below).


This project was funded by the National Geographic Society, the Smithsonian Institute, and the German Research Foundation (DFG).

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