Vampire bats may coordinate with `friends' over a bite to eat
Study tracks foraging behavior of 50 bats in the wild

Date:
September 23, 2021
Source:
Ohio State University
Summary:
Vampire bats that form bonds in captivity and continue those
'friendships' in the wild also hunt together, meeting up over a
meal after independent departures from the roost, according to a
new study.



FULL STORY ========================================================================== Vampire bats that form bonds in captivity and continue those "friendships"
in the wild also hunt together, meeting up over a meal after independent departures from the roost, according to a new study.


========================================================================== Researchers attached tiny "backpack" computers to 50 vampire bats --
some that had previously been in captivity together and others that had
lived only in the wild -- to track their movement during their nightly
foraging outings. By day, the bats shared a hollow tree in Panama, and
at night they obtained their meals by drinking blood from wounds they
made on cows in nearby pastures.

Tracking data showed that vampire bats set out to forage separately rather
than as a group -- and those that had established social relationships
would reunite during the hunt for what the researchers speculated was
some sort of coordination over food.

The findings suggest "making friends" in the roost could create more interdependence among socially bonded vampire bats -- meaning they
could benefit from each other's success at obtaining blood meals and
join forces when competing with other groups of bats for food resources.

"Everything we've been studying with vampire bats has looked at what
they're doing inside of a roost. What nobody has really known up until
now is whether these social relationships serve any function outside
the roost," said study co-author Gerald Carter, assistant professor of evolution, ecology and organismal biology at The Ohio State University.

"Understanding their interactions with a completely different group of
bats out on the pasture can help us understand what's going on inside
the colony. If every time they leave the roost they're getting into
battles, that can increase the amount of cooperation within the colony." Co-author Simon Ripperger, a former postdoctoral researcher in Carter's
lab, later supplemented the tracking data by capturing video and audio
of foraging vampire bats. He observed bats clustered together on one
cow and others atop separate cows, some drinking from different wounds
and some fighting over food access. He also made what are likely the
first audio recordings of a specific type of vampire bat vocalization associated with foraging.



==========================================================================
The research is published today (Sept. 23, 2021) in PLOS Biology.

The high-tech proximity sensors had already given the team a rare look
at how vampire bats maintained friendships they formed in captivity when
they returned to the wild. Over the course of two weeks, the backpack
computers placed on the 50 wild and formerly captive female bats produced
data on almost 400,000 individual meetings -- the information analyzed
for this new study.

By tracking foraging behaviors of both groups of bats, the researchers
were able to use the wild group as a control and simultaneously gauge
whether the lengthy captivity interfered with bats' ability to hunt --
which was not the case.

Carter and Ripperger considered a number of possible methods vampire bat "friends" would use to seek out food, ranging from not coordinating at
all to leaving the roost together and foraging as a group. Though the
proximity sensors couldn't provide details of where exactly the bats were
or what they were doing, the data on foraging encounters and previously published data on which bats groomed and shared food during captivity
combined to tell a pretty convincing story.

"We looked at the possibility of different scenarios, and we found
that they leave the roost to forage independently of each other, but
then the ones that have a relationship are somehow finding each other
and associating out on the cattle pasture -- and we think they're coordinating," Carter said.



==========================================================================
Bats that spent more time near each other in the roost during the day
also spent more time together outside at night and encountered each other
while foraging more frequently than bats not showing signs of social
bonds. Foraging encounters between bats that had close relationships were,
on average, longer in duration as well.

"If you think about it, a longer interaction is more likely to be
cooperative or affiliative than a short encounter, which could be neutral
or aggressive," Ripperger said.

The recorded vocalizations may eventually provide other insights about
vampire bats' social behaviors. Downward sweeping calls inside roosts and "buzz" calls during arguments had been documented before, but the calls recorded during the hunt, which increased and then decreased in frequency,
were distinct from those.

"I could see them vocalize even if they were alone on a cow, and they
vocalize back and forth, so we can tell that they interact while they're feeding," Ripperger said.

This work was conducted at and supported by the Smithsonian Tropical
Research Institute in Panama.

The study was funded by the National Science Foundation, the German
Research Foundation, a Smithsonian Scholarly Studies Awards grant and
a National Geographic Society Research Grant.

========================================================================== 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. Simon P. Ripperger, Gerald G. Carter. Social foraging in vampire
bats is
predicted by long-term cooperative relationships. PLOS Biology,
2021; 19 (9): e3001366 DOI: 10.1371/journal.pbio.3001366 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210923153316.htm

--- up 3 weeks, 8 hours, 25 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)