Bad at Goodbyes

Rough Transcript

Intro 00:05

Welcome to Bad at Goodbyes.

On today’s show we consider the Corsican Bat.

Species Information 02:05

The Corsican Bat is a critically endangered flying mammal native to the French island territory of Corsica in the Mediterranean Ocean, roughly 60 miles from the European mainland. Its scientific name is Myotis nustrale and it was first described, recently, in 2023.

Description

The Corsican Bat is small, generally about 2 inches in height from head to tail, with a roughly 10 inch wingspan and weighing only about a quarter of an ounce. One would easily fit in the palm of your hand.

 

Bats are mammals. And though they are the only mammal capable of true flight, they share typical mammalian qualities. For example, they are covered in short soft fur. The fur on their back (the dorsal side) is generally greyish-brown; the fur on their ventral side, that’s their chest and belly, is whitish-grey.

 

They have, like most mammals, a tiny bellybutton, a leftover from their mother’s umbilical cord.

 

Their wings are an extraordinary adaptation of mammalian forelimbs, our hands. A bat’s wing is basically a hand, with a small clawed thumb, and four really long finger bones. These skinny finger bones (metacarpals and phalanges) support the Patagium, that’s the wing membrane. The Patagium stretches between the fingers and connects to the side of their body and their hindlimbs (their feet). It is thin, flexible and strong, containing nerves, blood vessels and small muscles that allow the bat to control the wings shape for maneuverability and for flight.

 

The Corscian Bat’s hindlimbs are also specialized. Its knees bend backward, adapted for upside-down roosting. And each foot has five clawed toes, and specialized tendons, which allow the claws to lock in place, without using any muscles. Again an adaption for hanging upside down.

 

Their limbs and their face, which is not furred, are a pinkish, fleshy color. They have a long snout. A small nose, two very small dark eyes. And two relatively large fuzzy ears. Their genus, Myotis, are also called mouse-eared bats, if that helps paint a picture. The ears, protruding upright from the head, are roughly half an inch in length. And recall their total head and body length is under two inches, so that’s a lot of ear.

Behavior and Reproduction

Why such large ears, you may ask? For navigation. The Corsican Bat echolocates. Echolocation is like a biological sonar. The bat emits high-frequency sound pulses from specialized membranes in its throat that vibrate at extremely high frequencies, from roughly 13khz to 160kHz. For comparison, human hearing tops out at about 20khz. So the bat emits these ultrasonic frequencies, the sound waves travel outward, bouncing off objects in the environment, returning to the bat’s ears as a kind of echo. The bat’s specialized inner ear can perceive these high-pitched sounds with great fidelity, and their brain then analyzes the returning sound waves to build a detailed mental map of its surroundings, allowing it to determine the size, distance, and even texture of nearby objects. They have an innate ability to comprehend the speed of sound, and how quickly echoes return to them provides a high-resolution snapshot of their surroundings, able to discern large and very small objects; objects in motion; and differentiate between foreground and background objects.

 

They are not blind, and in fact have pretty good eyesight, but are nocturnal (they are mostly out at night) and mostly live in dark caves, so in these low-light environments they rely this auditory sense, echolocation, instead of their visual sense, their eyesight, to quote-unquote see their world.

 

Kate Derrick, a Scientific Officer, Community Manager, and Communications Manager, at the Groupe Chiroptères Corse, Corsica Bat Group very kindly sent us a recent recording she made with specialized ultrasonic equipment that allows us to hear the bat’s vocalizations, let’s have a listen to the Corsican Bat from their native habitat on Corsica.

 

[BAT CALLS]

 

So those were social calls, the Corsican Bat is highly social; they roost together in colonies of a few dozen to a few hundred individuals and will even roost among other bat species. There are 22 bat species on Corsica, though the Corscian bat is the only endemic bat, it is only found on Corsica.

 

The Corscian Bat has a kind of regular annual lifecycle rooted in this sociality. From roughly December until the end of February, they will hibernate. They gather in roosting colonies, in cliffside crevasses, caves and even in human made structures, for a three month period of wintertime dormancy: slowing their metabolism, conserving heat, breathing as infrequently as once per minute, with a heartrate less than 1% of normal. They do not eat or drink, instead, they live off the fat reserves they built up during warmer months.

 

Come spring they emerge, hungry. They will move to their hunting grounds, alpine forests and streams, feeding, at night, on a diet of small insects: flies, beetles, moths, spiders, earwigs. They find prey using their echolocation, plucking bugs from leaves and branches, and also hunting in the air, locating, capturing, and feeding while in flight. One bat eats roughly a third of its weight in insects per night, so several thousand insects consumed each night by a single individual. Bats, the Corsican Bat included, play a vital role in ecosystemic regulation.

 

So hibernation, feeding, and then come roughly May, nursery colonies are established and females begin to give birth; mothers birthing a single pup. Pups are altricial, meaning they are totally dependent on their mothers for survival. Born blind, without fur, without the ability to fly; relying entirely on their mothers for food, warmth, and protection.

 

Kate Derrick, from the Corsica Bat Group, talked to us about these colonies:

 

[Kate Derrick]

“And it’s just the females together and they will raise the young all together. They help each other out. The males during this time, they tend to be alone and they take no part in raising the young at all. It’s just the females. And they are basically super mothers. They will look after their baby so well. They’re mammals, so obviously they will give milk to their baby and the baby will spend most of its day just hanging out attached to its mum or next to its mum until night time where the mother will go out and feed herself and then come back every now and then to feed her young. And during this time, which is really interesting, usually you have one or two females that stay behind sort of just to keep an eye on everything and then they’ll swap places and go out and hunt and take turns.”

 

So, from roughly May-August mothers are birthing and communally raising new pups. Pups develop quickly, within a month or two, able to fly, and by end of summer able to fend for themselves.

 

So then August through October, is Corsican Bat mating season. Females leave their nursery colonies, and large numbers of females and males congregate, swarm, together to reproduce. Corsican Bat are polygynandrous, meaning both males and females have multiple mates.

 

But after mating, the female does not immediately become pregnant. Instead, she stores sperm in her reproductive tract, through the remaining autumn and through winter hibernation, providing nourishment to the sperm, keeping it viable for multiple months. Then emerging from dormancy, Spring triggers hormonal changes, the female releases an egg and fertilization finally occurs, with a roughly two month gestation period. And then we’re back to the nursery colony. The annual cycle, repeating again.

In The Dream

————

In the dream

 

Three months of dreaming.

To slow the breathe, to moderate the heart,

to quiet the anxious listener within,

to be so full and so ready for slumber.

 

To have one last lookabout, a silent sung lullaby, goodnight, 

And then to rest, nestled among kin, to still time, and sleep.

 

To sleep and to dream, first, of the strange sound of snow,

And then later, of Spring, and the waking-song of life abundant,

and of our place in that green opulence, a dream of flight,

 

As the beech is budding

As the brooke overflows with snowmelt

I am a veil in the moonlight, waving in the wind.

 

In the dream.

————

Habitat

The Corsican Bat is native to the French island territory of Corsica in the Mediterranean Ocean. Their population is spread among four distinct subpopulations that do not intermingle. One is in the northern center of the country near Corte, one is near Aitone in the west, one is near Bavella in the southeast, and one near Ghisoni in the middle of the island. In all of these places, our bat is found in very mountainous regions, ranging from roughly half a mile to one and a half miles above sea level, these are granite rocky peaks, cliffs, and outcrops surrounded by alpine forests of Silver Fir, European Beech, and Corsican Pine.

 

In general these mountain regions see mild summers with highs in the 80s°F and cold snowy winters with lows that dip into the 20s.

 

The Aitone and Bavella populations have been observed roosting in cliffside crevasses and caves. Specific roosting sites of the Corte population are as yet undiscovered. The Ghisoni population has established a nursery colony in human-built infrastructure, inside a tunnel of a hydroelectric dam. Again here’s Kate Derrick of the Corsica Bat Group:

 

[Kate Derrick]

“So they’re in this tunnel and the dam is owned by EDF, so our big French electrical company. So we went to them and said, “You need to protect this colony.” And they agreed, which is great. And we have a written agreement with them that we are allowed to visit the colony several times a year to do roost checks, and then if they ever do any work, they need to come through us first, which is great because obviously that helps us protect them. And they’re roosting with a huge colony of long-fingered bats. So they’re all there together. And there’s this tiny, tiny little kernel of Corsican Myotis. There’s only 100 of them, but they’re all grouped together on the ceiling of this dam.”

 

The Corsican Bat shares it mountain home with European Mouflon, Corsican Santolina, Corsican Nuthatch, Juniper, Corsican Snapdragon, Silver Birch, Corsican Fire Salamander, Bearded Vulture, Tyrrhenian Wall Lizard, European Beech, Silver Fir, Green Alder, Long-Fingered Bat, Sycamore Maple, Corsican Red Deer, Corsican Painted Frog, Corsican Pine, Corsican Brook Salamander, Alpine Long-Eared Bat, and many many more.

Threats

One main threat to the Corsican Bat is its low population. Species with low populations, and particularly social species who live in groups, are more vulnerable to stochastic events, random, unpredictable occurrences that could prove fatal for many many individuals all at once. So a cave-in for example, or a quickly spreading disease.

 

Human induced climate change is an imminent threat. Changing weather patterns and the frequency and severity of extreme weather increase the likelihood of stochastic events. And as global temperatures rise, the Corsican Bat may be forced to move further up the mountains to find suitably cool habitat. However, the bats cannot move much higher because they already live at nearly peak elevations.

 

Additionally potential human disturbance threatens the bats. So obviously the nursery roost at the dam site is of concern, and the mountain sites, though remote, do attract hikers and rock-climbers.

Conservation

Fortunately all the Corsican Bats’ known roosts fall within the Parc Naturel Régional de Corse, protected wilderness, that covers over 40% of the island.

 

Additionally the Corsica Bat Group, Groupe Chiroptères Corse has a range of dedicated programs in place to help conserve the species. Here again is Kate Derrick (Community Manager, Communications Manager, Scientific Officer at the org) to share what they are doing.

 

[Kate Derrick]

“It’s an NGO situated in Corsica and we are specialized in bat study, protection, and awareness for all bats, all across Corsica. Our main reason for existing is to know everything we can about all of our species. My specialty, my personal specialty is acoustics, so bat acoustics. So basically studying their calls. They emit ultrasounds and each species has their own call. So um you can learn a lot just by putting out a bat recorder and listening.

We obviously do as many scientific studies as we can to map out roosts and hunting grounds. We did a lot of radio tracking. We just try to find as many roosts as we can because of course the idea is one, to know where these bats are, how are they living, and also, we need to protect these roosts. We need to know where they are so we can protect them, whether it’s um governmental protection or some caves we found, for example, we’ve set up laws so people cannot actually go in there, and even sometimes you can even put gates up around or fencing around just so people can’t randomly go into the cave.

The second part of what we do is communication. So, it’s quite well known that bats aren’t particularly liked by the general public. Luckily that idea is changing bit by bit. So I, I do talks in schools, I go into schools, I talk to children about bats to just show them that they’re not scary. They’re also very interesting, they’re quite beautiful if you look at them, and they’re all very different. And what can we do to help bats? And the kids absolutely love it. They’re always so happy and interested and I talk to the general public, I do bat nights. I also do all the social media and stuff. It’s just sharing everything we do, why bats are important, why we should protect them.

And the last thing, we have a helpline for when people have bats in their homes or when they have a project and they don’t know what to do because a lot of times they will have bats maybe roosting in their attic, maybe in their garage, and they’re like, “Please come take these bats away.” Usually it’s like this, what do I do with these bats? And um so I’m there to give them advice and sometimes I will go visit and I will help them. We sometimes get calls for sick bats as well. If someone’s found a bat on the floor, if maybe their cat’s caught a bat, which happens a lot. We help them either take them to the vet or sort them out, or I do take in sick bats and I look after them. It’s quite a lovely experience. I’ve had, this year in particular, I had five babies that came in, little babies that need to be given milk, and I managed to make them grow up and fly. And it was um beautiful and very emotional. You get very attached to them.

So yeah, it’s very very very diverse work. We will keep studying them because we want to know as much as we can about them, and raise as much awareness as we can about these bats as well, because they’re really important to the island and it’s it’s a gift really for the island as well, having our own species and um it’s just a testament to how how special the island is and how special the species are.”

The Corsican Bat has been considered critically endangered on the IUCN Red List since 2024.

 

Our most recent counts estimate that less than 1000 Corsican Bat remain in the wild.

Citations 30:46

Information for today’s show about the Corsican Bat was compiled from:

 

Aulagnier, S., Beuneux, G. & Russo, D. 2024. Myotis nustrale. The IUCN Red List of Threatened Species 2024: e.T248107314A248107503. – https://dx.doi.org/10.2305/IUCN.UK.2024-2.RLTS.T248107314A248107503.en

 

Derrick, K. Groupe Chiroptères Corse (Community Manager, Communications Manager, Scientific Officer). Interview by Joshua Dumas, October 30, 2025

 

Derrick, K. and Beuneux, G. 2024. L’espèce endémique de Corse, Myotis nustrale, enfin décrite officiellement ! Envol des Chiros 36: 12-13. – https://www.sfepm.org/sites/default/files/inline-files/EDC36.pdf

 

Groupe chiroptères Corse, 2019 - Programme d’étude concernant l’amélioration des connaissances sur l’écologie d’une nouvelle espèce de chauve-souris endémique à la Corse : Myotis sp. C (ex - Myotis nattereri) - Année 2018 – https://gaia.oec.fr/documents/39037ba8a97630e6c387281c39766ece.pdf

 

Javier Juste, Manuel Ruedi, Sébastien J. Puechmaille, Irene Salicini, Carlos Ibáñez “Two New Cryptic Bat Species within the Myotis nattereri Species Complex (Vespertilionidae, Chiroptera) from the Western Palaearctic,” Acta Chiropterologica, 20(2), 285-300, (14 February 2019) – https://doi.org/10.3161/15081109ACC2018.20.2.001

 

Martinetti, Jean-Michel dir. Belle de Nuit. France 3 Corse ViaStella and Mediterranean Dream Productions, 2024. 52 min – https://www.france.tv/france-3/corse-viastella/corsica-salvatica/6717952-regards-croises-sur-le-monde-animal.html

 

Office de l’Environnement de la Corse. Faune Sauvage de Corse. Murin de Corse. – https://faunesauvagedecorse.oec.fr/Espece_mpage_224_idtaxon,4905.htm

 

One Earth – https://www.oneearth.org/ecoregions/corsican-montane-broadleaf-and-mixed-forests/

 

Schmidbauer, P., & Denzinger, A. (2019). Social calls of Myotis nattereri during swarming: Call structure mirrors the different behavioral context. PloS one, 14(9), e0221792. – https://doi.org/10.1371/journal.pone.0221792

 

Sébastien J. Puechmaille, Benjamin Allegrini, Emma S.M. Boston, Marie-Jo Dubourg-Savage, Allowen Evin, Alexandre Knochel, Yann Le Bris, Vincent Lecoq, Michèle Lemaire, Delphine Rist, Emma C. Teeling. Genetic analyses reveal further cryptic lineages within the Myotis nattereri species complex. Mammalian Biology, Volume 77, Issue 3, 2012, Pages 224-228. – https://doi.org/10.1016/j.mambio.2011.11.004

 

Sébastien J. Puechmaille, Serena Dool, Gregory Beuneux, Manuel Ruedi “Newly described and already endangered: a new mammal species endemic to Corsica,” Revue suisse de Zoologie, 130(2), 335-351, (18 October 2023) – https://doi.org/10.35929/RSZ.0108

 

Stoecklé, Tanguy and Amiguet, Marie, dir. Les Ailes du Maquis. Stéphane Quinson and Les Films du Tambour de Soie, 2021. 52 min. – https://www.youtube.com/watch?v=MDDDnAfMbFQ

For more information about Corsican Bat conservation see the Corsica Bat Group, in French: Groupe Chiroptères Corse at https://chauvesouriscorse.fr

 

And lastly I would like to express my deep gratitude to Kate Derrick at the Corsica Bat Group for sharing her expertise, insights and her work with us today. It was so inspiring to speak with her.

Music 32:42

Pledge 40:26

I honor the lifeforce of the Corsican Bat. I will commit its name to my record. I am grateful to have shared time on our planet with this being. I lament the ways in which I and my species have harmed and diminished this species. I grieve.

 

And so, in the name of the Corsican Bat I pledge to reduce my consumption. And my carbon footprint. And curb my wastefulness. I pledge to acknowledge and attempt to address the costs of my actions and inactions. And I pledge to resist the harm of plant and animal kin and their habitat, by individuals, corporations, and governments.

 

I forever pledge my song to the witness and memory of all life, to a broad celebration of biodiversity, and to the total liberation of all beings.