Lab updates: May 2019

PhD student Imran Razik was awarded both a Short-term Fellowship from the Smithsonian Tropical Research Institute and a Student Research Grant from the Animal Behavior Society. He will be studying urinary oxytocin as a predictor of variation in grooming and food-sharing between both old (familiar) and new (unfamiliar) individuals.

MSc student Bridget Brown was awarded a Critical Difference to Women Scholarship. She used this money to fund her travel to Panama where she is studying possible chemical cues for roost-finding in bats.

This summer, PhD Student Theresa Chen will be working with Michael Taborsky at the University of Bern, Switzerland, working on information used by rats to make decisions to cooperate.

Imran, Bridget, and Gerry will be at the Smithsonian Tropical Research Institute in Panama. We will be working with Simon Ripperger, Sebastian Stockmaier, Hanna Weiser, and Rachel Page on vampire bat social networks.

The work of two of our past interns, Jineth Berrío-Martínez and Sam Kaiser, entitled The role of past experience in the development of feeding behavior in common vampire bats was recently accepted with minor revisions in the journal PeerJ.

I recently published a paper entitled Challenges with assessing the roles of nepotism and reciprocity in cooperation networks  in the journal Animal Behavior. I should maybe write a separate post about that when I have time…

Rachelle Adams and I are now co-teaching the field course Tropical Behavioral Ecology and Evolution in Panama. I am going to learn a lot about ants!

A few other recent and relevant articles:

Jerry Wilkinson and Danielle Adams recently published an interesting paper on Recurrent evolution of extreme longevity in bats

Observing grooming promotes affiliation in Barbary macaques

Evidence for reconciliation between males and females in wild chacma baboons

A recent paper on the seed dispersal services provided by African fruit bats

On the evolution of human food sharing behavior norms

Popular article in American Scientist on work by Daniel Streicker’s group: Glow-in-the-Dark Vampire Bats Could Help Curtail Rabies

Posted in News | Leave a comment

Feb 2019 updates

Simon Ripperger will be joining our team this summer in Panama. Simon recently published the first paper on his new method for sampling dynamic social networks of whole groups of bats in the field. The paper in Biology Letters is entitled “Proximity sensors on common noctule bats reveal evidence that mothers guide juveniles to roosts but not food and it was featured in the “research highlights” section of Nature.

Cooperation in vampire bats was also recently featured in this UK magazine called Bat News:

I posted a preprint for a manuscript, currently in review, called Development of new food-sharing relationships among nonkin vampire bats and The Journal Coverage Podcast interviewed me for a podcast episode about it. We also talk a tiny bit about preprints and why they are great. Here’s a short video about preprints by organization ASAPbio:

Finally, as I am writing my first big NSF grant, I came across this interesting analysis. This quote sums it up:

We find that the effort researchers waste in writing proposals may be comparable to the total scientific value of the research that the funding supports…

Although I would add to this idea that writing proposals is not always a wasted effort because it is also an intellectually creative, worthwhile, and fun thing to do on its own. The basic problem is that so many good ideas are not funded and are therefore never made public. Maybe we should publish proposals: “This is what I would do in my lab with a million dollars.” Then if someone else “steals” your research project idea, they could cite your proposal to say “this is where I got this idea” or the author of the proposal would be an author on the paper that actually carried it out. This could encourage more sharing of ideas and data?

Posted in About science as an activity, About vampire bats, News, People | Leave a comment

New paper on relatedness and social networks across different bats

Last year, I attended a symposium hosted by Peter Kappeler at the German Primate Center on the topic of “social complexity”. A bunch of evolutionary and behavioral ecologists from different backgrounds got together to argue about stuff like ‘How should we define social complexity?’, ‘Is the brain size of a species a good of measure of social complexity? (or anything at all?) and “Why does Germany have so much more science funding than us?”

This was actually one of the best conferences I attended, I met a bunch of people whose work I’d read, and I started useful collaborations, including one with a Msc student working on neophobia, who convinced me that bats reacting to novel objects was actually interesting and helped me write this paper. With others from Damien Farine’s lab, I wrote my opinion about the conference here.

What’s more socially complex: a bee or a chimp? (Answer: vampire bat). Biologists tend to define social complexity in such as way that their animal is one of the ‘complex ones’. One possible solution to this that I liked for talking about social complexity was the terms proposed by Dieter Lukas and Tim Clutton-Brock: “organizational complexity” (exemplified by cooperative breeders and eusocial insects which have a division of reproduction and labor) and “relational complexity” (exemplified by animals with individualized relationships like some primates, elephants, and of course vampire bats). They published evidence for these distinct dimensions of complexity in mammals here. Others suggested other frameworks.*

The invited speakers were asked to write up their talks as papers for this special issue in Behavioral Ecology and Sociobiology. I gave a talk about vampire bats and I contributed to an invited talk/paper on social complexity across bats, led by Jerry Wilkinson.

An example of social networks in three bats and probably some copyright violations.

Here’s the link to that paper, Kinship, association, and social complexity in bats (if that link doesn’t work look under “publications” above). The basic idea is that comparing social networks across species is actually quite difficult and rarely done because different studies measure ‘groups’ and ‘associations’ differently across species. But bat researchers tend to do the same thing: we individually mark bats, then observe which bats are in a roost across different days, and when we mark them, we collect a tissue sample to estimate their genetic relatedness. Several people have done this over several years. So Jerry gathered all the data together from different researchers that have done long-term studies** and we did the same basic social network analyses in each species to see if anything interesting came up.

To be honest, there wasn’t anything too surprising if you know the social and genetic structures of these different bat species, but it was quite nice to put it all together in one place and to measure all these species using the same metrics. For some species, it did change my picture of their social structures as being a bit more ‘messy’ that I thought. I also noticed was that we actually had different conclusions about relatedness and association for some species than previous published analyses, suggesting that the details of how you measure relatedness and association can determine what you conclude. Another lesson was that the link between relatedness and association can depend a lot on what your null model accounts for. This is something Damien has often written about. For example, if two individuals are always seen together but always in the same roost, then do they actually prefer roosting near each other or do they just prefer the same roost and they don’t actually care about each other? It’s actually easier to infer social structure for animals that switch roosts and move around because you can account for spatial effects. Another example is that a null model that does not account for time effects could lead to the idea that two individuals are highly associated simply because they both died in the first year of the study. Social networks are inherently correlational, and it’s quite easy to draw the wrong conclusions if you don’t think about and correct for these kinds of biases.

Another nice thing that you don’t see in the paper is that we ran all the same analyses in both Matlab (‘Socprog’ by Hal Whitehead) and R (‘asnipe’ by Damien Farine) to test if both packages gave the same results and if not, why not. Given all the possible ways to do things, not all of the analyses we did ended up in the paper, and I think there’s a lot more that could possibly be tested. For example, if we could get reliable maternity data, perhaps we could test for evidence of within-group maternal inheritance of associations (if you’re reading this and want to see if this analysis is feasible, feel free to email me).

*_One could also look at animal social complexity not as just understood by us biologists but more from the perspective of mathematicians who study ‘complexity science’. Liz Hobson and others at the amazing and lovely Santa Fe Institute wrote a paper on this (preprint here).

** Jerry Wilkinson had data on evening bats in the USA. Wilkinson and Kisi Bohn’s had data on greater-spear nosed bats in Trinidad. Mirjam Knörnschild, Linus Günther, Barbara Caspers, Martina Nagy, and Frieder Mayer provided data on sac-winged bats and proboscis bats in Costa Rica. Gloriana Chaverri had data on disc-winged bats in Costa Rica. Gerald Kerth had data on Bechstein’s bats in Germany. Jorge Ortega had data on Jamaican fruit bats kin Mexico. Krista Patriquin had data on Northern long-eared bats in Canada. Bryan Arnold (Pallid bats) and Dina Dechmann (Lophostoma silvicolum, the bats that live in active termite nests) also contributed data but were not included in the study because the data were too sparse to estimate good networks. Victoria Flores and Rachel Page will soon be adding the frog-eating bat to this comparative dataset.

Posted in About vampire bats, News | Leave a comment

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”

Posted in News | Leave a comment

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.

Posted in People | Leave a comment

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.

Posted in People | Leave a comment

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!


Posted in News | Leave a comment