From the archive: Bat signals
Many Minds
The Relationship Between Group Size and Information Content in a Specific Vocalization Type
There's fairly good evidence now in some words and also in primates and carnivores that there is a positive relationship, at least, obviously. We find the correlation between group size and either repertoire size or information content in a specific vocalization type. And so you've observed this same relationship within bats recently, is that right? That's right. For that, we looked at different vocalization types that are used in specific social contexts and different bat species.
We're still on summer break, but we wanted to share a favorite interview from our archives. Enjoy!
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We’ve got something special for you today folks: bats. That’s right: bats.
Ever since Thomas Nagel wrote his famous essay on what it’s like to be a bat, these flying, furry, nocturnal, shrieky mammals have taken up roost in our scientific imaginations. They’ve become a kind of poster child—or poster creature?—for the idea that our world is full of truly alien minds, inhabiting otherworldly lifeworlds. On today’s show, we dive deep into these other minds—and into some of their less appreciated capacities. Bats don’t just echolocate, they also sing. And, as we’ll see, they sing with gusto.
My guest today is Dr. Mirjam Knörnschild. She directs the Behavioral Ecology and Bioacoustics Lab at the Natural History Museum of Berlin. She and her team study bat communication, cognition, and social life; they focus in particular on bat social vocalizations—what we might call bat signals.
Here, we do a bit of Bats 101. We talk about how bats form a spectacularly diverse group, or taxon. We talk about the mechanics of echolocation. We talk about the mind-bogglingly boisterous acoustic world of bats and how they’re able to navigate it. We discuss Mirjam and her team's recent paper in Science magazine, showing that baby bat pups babble much like human infants. And, last but not least, we talk about what it's like to be a bat.
As I say in this conversation, I've always been a bit unnerved by bats, but part of me also knew they were seriously cool. But really, I didn't know the half of it. There's so much more to these creatures than meets the casual eye.
One last thing before we jump in: as a little bonus, for this episode Mirjam was kind enough to share some examples of the bat calls we discuss in the episode. So there’s a bit of an audio appendix at the end where you can hear slowed-down versions.
On to my chat with Dr. Mirjam Knörnschild. Enjoy!
A transcript of this episode is available here.
Notes and links
7:20 – Meet the Honduran white bat, which Knörnschild likens to a “fluffy little white ping pong ball.”
13:50 – Austin, Texas is home to Bracken Cave, which harbors more than 15 million bats.
16:30 – Much of Dr. Knörnschild’s work focuses on the Greater Sac-winged bat, which is a member of the Emballonurid family.
18:00 – See the audio appendix for an example of a Greater Sac-winged bat’s echolocation calls. See also examples on Dr. Knörnschild’s website.
21:10 – A paper by Dr. Knörnschild and colleagues about how echolocation calls serve social functions in addition to navigational functions.
24:00 – A paper by Dr. Knörnschild and colleagues on the origin and diversity of bat songs.
30:00 – A recent paper by Dr. Knörnschild and colleagues on the correlation between social complexity and vocal complexity across bat species.
37:30 – A brand new special issue on vocal learning in humans and animals, including a review of vocal learning in mammals by Dr. Vincent Janik and Dr. Knörnschild.
40:35 – Dr. Knörnschild’s first scientific paper, in 2006, reported the observation that Greater Sac-winged bats seemed to babble like infants.
47:20 – A recent paper by Dr. Knörnschild and colleagues on territorial songs in male Greater Sac-winged bats.
53:45 – A very recently published paper in Science by Ahana Fernandez, Dr. Knörnschild, and collaborators; see also this popular article and a video about the findings.
1:05:30 – A recent paper by Dr. Knörnschild and colleagues on bat “motherese.”
1:12:00 – For a concise narrative summary of Dr. Knörnschild’s research, including some of the future directions she is planning to pursue, see the article ‘Bats in translation.’
1:14:00 – The philosopher Thomas Nagel famously argued that we can’t really know what it’s like to be a bat.
Dr. Knörnschild recommends two books by Merlin Tuttle:
Bats: An Illustrated Guide to All Species
You can find Dr. Knörnschild on Twitter (@MKnornschild) and follow her research at her website.
Many Minds is a project of the Diverse Intelligences Summer Institute, which is made possible by a generous grant from the Templeton World Charity Foundation to UCLA. It is hosted and produced by Kensy Cooperrider, with help from Assistant Producer Urte Laukaityte and with creative support from DISI Directors Erica Cartmill and Jacob Foster. Our artwork is by Ben Oldroyd. Our transcripts are created by Sarah Dopierala.
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