Like college roommates, vampire bats bond when randomly paired
Researchers test how friendships might form in the wild
Date:
April 6, 2022
Source:
Ohio State University
Summary:
Social bonding between randomly assigned college roommates
is not only a human phenomenon, a new study on vampire bats
suggests. Vampire bat pairs that were forced to live together for
only one week sustained their friendly relationships for more than
two months after they were released into a bigger bat community.
FULL STORY ========================================================================== Social bonding between randomly assigned college roommates is not only
a human phenomenon, a new study on vampire bats suggests.
========================================================================== Vampire bat pairs that were forced to live together for only one week
sustained their friendly relationships for more than two months after
they were released into a bigger bat community.
The study provides rare findings about wild animal social behavior that
are based on precisely measured effects of relationship manipulation
rather than on observation alone.
"The process of how social bonds form is this fundamentally mysterious
thing that a lot of people are interested in, but have very different interpretations of how it happens," said Gerald Carter, senior author of
the study and assistant professor of evolution, ecology and organismal
biology at The Ohio State University.
"We're trying to build vampire bats as a system where we can directly
test these interpretations. In this experiment, we forced them together
for a short amount of time and then measured their grooming rates, which increased by a specific amount over a period of time. It just hasn't
really been done before." The study was conducted by Imran Razik with
help from Bridget Brown, both Ohio State graduate students in evolution, ecology and organismal biology. Carter and Razik are also affiliates of
the Smithsonian Tropical Research Institute in Panama, where the study
took place.
==========================================================================
The research is published in the journal Biology Letters.
The team captured seven adult female vampire bats from each of three
distantly located roosts to assemble the colony of 21 bats for the study.
For the first six weeks, the vampire bats mingled together freely among familiar roost mates and strangers from the other roosts. Next, during
the treatment phase, researchers split the bats into seven smaller
groups. For each group, they selected one bat from each of the three
sites and forced them to live together as a trio for seven days.
Pairs of bats that lived together were identified as test pairs whose
grooming behavior was compared to two other types of pairs -- control
pairs that were not forced into proximity, and familiar pairs of bats
that were caught from the same roost.
Following the treatment period, all of the bats lived freely together
again for nine weeks.
========================================================================== During the three study phases, Razik observed and measured all bat
grooming interactions of 5 seconds or longer that were captured by three infrared surveillance cameras operating for six hours each day.
"From early on, they had potential to start grooming relationships, and
then we did the forced proximity phase to see if we could increase the
rates of grooming in random pairs. We then measured grooming during the post-treatment phase to compare pre- versus post-treatment grooming,"
Razik said.
Results showed, based on the overall mean change in social grooming rates,
that the forced proximity phase increased social grooming in test pairs
more than in control and familiar pairs.
"It was a striking pattern," Carter said. "One thing you might imagine
is that, after these bats are in their 'college dorm room' together,
they stay together for a little while afterward but that quickly goes
away -- but we didn't see that. The test bats were still grooming each
other more than the control bats even at the end of the experiment,
nine weeks later." Razik noted that many of the new test pairs had done
some reciprocal grooming in the first six weeks, but the team focused
their analysis on the effect of the randomly assigned forced proximity treatment in shaping lasting social bonds.
"During the forced proximity phase, each bat had two partners with whom
they could interact, and in the post-treatment phase they had at least 20
other available partners -- even some they knew beforehand that had been captured from the same site," he said. "So the fact that the preference
was visible and clear and throughout the entire nine weeks is a meaningful result -- and the effect was clear in all the ways we statistically
analyzed the data." This single study does not settle the question of
how social bonds form in the wild, which are considered important for
animal health, well-being, survival and reproductive success. Scholarly
debate continues on the relative importance of potential causal factors:
Are animals drawn to others with similar characteristics, or do opposites attract? Is merely living in close proximity sufficient to become friends,
or are bonds formed by giving each other help? "What this experiment
tells us is there is a causal relationship between being forced into
the same space and actually having a preference for each other later,"
Carter said. "Which is why the college dorm room is a perfect example:
You get randomly paired with somebody and because of that, you continue to
seek that person out later. There's a relationship that formed. It might
be really obvious for humans, but we don't know to what extent this is happening in other animals." This work was supported by the STRI, the
Animal Behavior Society, an Ohio State graduate enrichment fellowship,
Sigma Chi, a Critical Difference for Women Development Grant from Ohio
State and the National Science Foundation.
Video:
https://youtu.be/sbID6WKxQ-A
========================================================================== Story Source: Materials provided by Ohio_State_University. Original
written by Emily Caldwell. Note: Content may be edited for style and
length.
========================================================================== Journal Reference:
1. Imran Razik, Bridget K. G. Brown, Gerald G. Carter. Forced proximity
promotes the formation of enduring cooperative relationships
in vampire bats. Biology Letters, 2022; 18 (4) DOI:
10.1098/rsbl.2022.0056 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/04/220406101740.htm
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