New preprint: Evidence for unfamiliar kin recognition in vampire bats

… by Simon Ripperger, Rachel Page, Frieder Mayer, and Gerry Carter. I would love to get early feedback on this one, so please email me if you have any. We submitted it to Biology Letters. Here’s the preprint (what’s a preprint?) at BioRxiv:

Common vampire bat (Traer Scott)

ABSTRACT: Kin discrimination allows organisms to preferentially cooperate with kin, reduce kin competition, and avoid inbreeding. In vertebrates, kin discrimination often occurs through prior association. There is less evidence for recognition of unfamiliar kin. Here, we present the first evidence of unfamiliar kin recognition in bats. We captured female vampire bats (Desmodus rotundus) from a single roost, allowed them to breed in captivity for 22 months, then released 17 wild-caught females and six captive-born daughters back into the same wild roost. We then used custom-built proximity sensors to track the free-ranging social encounters among the previously captive bats and 27 tagged control bats from the same roost. Using microsatellite-based relatedness estimates, we found that previously captive bats preferentially associated with related control bats, and that captive-born bats preferentially associated with unfamiliar kin among control bats. Closer analyses showed that these unfamiliar-kin-biased associations were not caused by mothers or other familiar close kin, because the kinship bias was evident even when those bats were not nearby. This striking evidence for unfamiliar kin recognition in vampire bats warrants further investigation and provides new hypotheses for how cooperative relationships might be driven synergistically by both social experience and phenotypic similarity.

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Vote for our lab! You can vote every day until Dec 31!

The study from our previous post was selected as one of the 5 competitors for “Coolest Science Story of the Year” at The Ohio State University. LINK:

Please vote for us and spread the word! Everyone can actually vote multiple times: every day until Dec 31.

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New paper: Vampire bats that cooperate in the lab maintain their social networks in the wild

Here’s the paper in Current Biology. The press coverage included PBS, CNN, NPR , BBC, Nature Magazine, Science Magazine, Science News, Popular Science, The Ohio State University, Cosmos Magazine, Wissenschaft, El Mundo, ZME Science, SciShow, and EurekaAlert Press release (video below).

Take home message: Halloween is a good day to publish a paper on vampire bats!

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Latest paper suggests there are two kinds social grooming in vampire bats (and some other updates)

A recent paper from our group (Team Vampire 2017) suggests that vampire bats might perform two different kinds of social grooming. First, a focal vampire bat is more likely to start allogrooming a bat next to them right after grooming themselves. Imagine a cat in your lap that is licking itself and then starts licking your hand. We call these events ‘actor-driven allogrooming’ because they are initiated by the actor.

Second, a vampire bat is also more likely to allogroom another bat that is currently self-grooming, like in this video clip I posted on twitter:

We call this ‘receiver-driven allogrooming’ and we suggest it could even be a response to need (i.e. the allogroomer might be actually ‘helping’ the receiver). This interpretation is consistent with the observation that vampire bats are more likely to allogroom a bat that has wetted and disturbed fur (even independent of the recipient’s increased self-grooming). It’s also consistent with the observation that allogrooming a past stranger increases the probability of a new food-sharing bond forming (paper in review).

Why do we classify these separately rather than consider them as two different factors that both make allogrooming more likely? Because actor self-grooming and receiver self-grooming do not combine to make allogrooming even more likely in the next moment. Instead, they conflict: a bat that is grooming itself is actually less likely to do receiver-driven allogrooming. An actor-driven allogroomer is less likely to be influenced by what the other bat is doing.

Our interpretation is that some kinds of allogrooming (the receiver-driven kind) might be responses to the recipient’s need, while other kinds might just be a bat extending its self-grooming to lick the fur or wings of others (and are not some form of targeted helping). Perhaps this is why some studies on primates find that social grooming reduces stress in the recipients, whereas others find that is only beneficial for the actors. The effect might all depend on whether the social grooming is internally motivated or a response to a need.

Sometimes I ask my wife to scratch a spot on my back that I can’t reach, and that is some great ‘receiver-driven allogrooming’ and a helpful response to need. But sometimes our cat likes to lick the salt in my hair, or a dog licks your face, or my wife likes to pick at things on my skin, and that is ‘actor-driven allogrooming’ which is… less helpful.

This project was led by MSc student and Smithsonian Tropical Research Institute intern Hugo Narizano. The PDF of this paper can be found under “Publications”

In other news…

A recent paper on vampire bat-transmitted rabies from Daniel Streicker’s lab analyzed 14 years of rabies virus genetic data from Costa Rica. They found that rabies virus was unexpectedly dispersing into Costa Rica from both the north and south. Costa Rica has had outbreaks of vampire bat rabies on and off since 1985. But rather than rabies being endemic, different lineages of rabies have been repeatedly invading and going extinct.

There were some interesting conceptual papers on animal social network analysis this year: one on using concepts from complexity science, another reviewing the uses of multi-layer networks, and another making the argument for ‘networks within networks’.

Our 2019 Panama field season is drawing to a close this month.

Dr. Angela Freeman has just arrived in Panama from Cornell University. Since 2017, we have been collaborating on a project to look at oxytocin and vasopressin receptors in the brain as a predictor of cooperativeness in bats.

My PhD student Imran Razik is finishing his final behavioral tests tomorrow! Over the last six months, Imran led a team of people–including Lovisa Duck, Dini Aparicio, Bridget Brown, David Girbino, Cynthia Marroquin, Emma Kline, Basti Stockmaier, and Gregg Cohen– that has already collected the times and durations of over 10,700+ grooming interactions and 700+ begging or food-sharing interactions in a captive colony with bats introduced from three sites.

Lab Members Imran Razik, Bridget Brown, Simon Ripperger, Cynthia Marroquin, and I will be presenting at the North American bat meetings in Michigan this month.

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New Course

I’m also now officially a Research Associate at the Smithsonian Tropical Research Institute.

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Can a captive-born vampire bat feed on a live animal?

In 2016 and 2017, we captured female vampire bats and then released them back into the wild almost two years later to track their wild association networks. During their time in captivity, 12 of the females gave birth to pups. Would these captive-born bats be able to survive in the wild?

Jineth Berrío-Martínez conducted an experiment on whether the captive-born bats could feed on a live chicken (alone or with the presence of their mother).

First, we decided to buy a bunch of chickens to use as hosts. My wife Michelle, who is a farmer, helped us build a chicken coop that was secure against predators.

The chicken coop in construction (and the vampire house in the background)

Jineth and Michelle
The finished coop and chicken pen. Free eggs!

Each day, Jineth would isolate a chicken and a vampire bat and film the feeding. Some of the results were unclear and unexpected. For example the mothers never fed on the chickens (see the paper for more information), but we did answer the main question: yes captive born bats can feed on a live animal.

Jineth tried a number of different setups in a series of pilot trials before finding one that worked well. The vampire bat had to be able to access the chicken but also get away from it. The example below shows a cage that a vampire bat could enter and exit but not the chicken. We used a different setup in the actual tests (see the videos below) where the bat could hide in roost box.

Here is a video showing a captive-born bat feeding on a live animal for the first time.

We had previously found that younger bats are far more exploratory and more likely to crawl and jump on top of novel objects, and we observed that this was equally true when feeding on novel live animals! Overall, it seemed that the young vampire bats could feed on a live animal, but they were not particularly good at it when compared to some wild-caught vampire bats. We could not compare them with their mothers however, because none of the mothers even tried to feed on the chicken. Instead, they hid in their roost box the whole night.

Sam Kaiser also did an experiment testing whether captive-born or wild-born bats prefer cold blood (which is what we give them in captivity) or warm blood (which is what they would feed on in the wild). It turns out that the vampire bats don’t really care much at all about the blood temperature when the blood is in a feeder spout. This might seem a bit surprising because vampire bats use heat to find blood near the skin, but it’s not too surprising to consider that vampire bats use many different cues (echolocation, olfaction, vision, etc) and they probably learn to use different cues in different contexts.

Study: Berrío-Martínez J, Kaiser S, Nowak M, Page RA, Carter GG. 2019. The role of past experience in development of feeding behavior in common vampire bats. PeerJ 7:e7448

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Lab updates: July 2019

At the end of May, Rachelle Adams and I finished teaching the course “Tropical Behavioral Ecology and Evolution” in Panama. Each student worked on an individual research project and also wrote a blog post about another student’s project.

Tropical Behavioral Ecology and Evolution, May 2019

In June, students Imran Razik, Bridget Brown, and David Girbino were joined by Cynthia Marroquin and Emma Kline. Simon Ripperger and Hanna Wesier also joined up with us from Germany. Dineilys Aparicio is helping us as an intern.

Team Vampire Summer 2019
Left to right: Dini, Bridget, Simon, Basti, Gerry, Imran, David, Cynthia, and Emma

Imran is continuing work on cooperative relationships in vampire bats by looking at variation in urinary oxytocin as a predictor of grooming and food-sharing. Bridget is studying if bats use olfaction to select roosting sites. David is looking at how “first impressions’ between vampire bats as strangers might predict their relationship development. He is also helping us look at individuality in the echolocation calls (a student project led by Amy Luo). Cynthia is looking at individual variation in metabolic rate in bats. Emma is looking at the effects of proximity loggers on bat behavior. Simon is tracking social networks in the wild. Hanna is testing a mobile bat-mounted ECG to measure heart rates.

Basti is continuing his work on sickness behavior in vampire bats. This week at the The Animal Behavior Society Meeting, he is giving a talk on Wednesday entitled Effects of sickness on social networks depend on the type of behaviour, measure, and relationship. His manuscript for this work is currently in revision for Journal of Animal Ecology. At this same meeting, I’m giving a talk on how vampire bats maintain their cooperative relationships from the lab to the field (Friday, after the lunch break).

Theresa Chen is in Switzerland working on cooperation in rats in Michael Taborsky’s lab.

A paper by Ivar Vleut, myself, and Rodrigo Medellin entitled Movement ecology of the carnivorous woolly false vampire bat (Chrotopterus auritus) in southern Mexico was recently accepted at PLOS One and should be out shortly.

Simon did some great work on developing sites for tracking social roosting and foraging networks. Check out this 30-second clip of some footage he took by staying up all night in a cattle pasture with an infrared video camera. It shows vampire bats competing with each other over wound sites on cattle.

Simon and I are finally in the process of publishing our work on developing new cooperative relationships (in review at PNAS), strengthening existing relationships, then tracking associations between previously captive bats released back into the wild (to be submitted this week). We used dynamic network analyses to look at how their captive relationships persisted and changed in the transition from the lab back to the wild.

This year we are studying a captive colony. Two of these were bats we captured in December 2015, studied in captivity from 2016-2017, released and studied in the wild in 2017, and now re-captured and being studied again in 2019! During this time, we have seen how these bat interact with more than 30 unfamiliar individuals over the course of about 17 months. Getting many repeated measures in the social or cooperative behavior of individuals across different contexts is key to understanding why some individuals are more ‘generous’ in their grooming and food-sharing.

To extend this work, I am writing an NSF grant with Ian Hamilton and Elizabeth Hobson.

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