What it is like to save a bat

Interview with Dr. Konstantin Deininger, Dr. Claudia Towne Hirtenfelder, and Katharina Leibezeder

In this interview, I chat with Konstantin, Claudia and Kathy about an impressive Viennese bat rehabilitation project that works to ensure bats in need receive proper care – and which we cover for “Philosophy in the Wild. Finding Hope in Mixed Communities”.

• Konstantin is a philosopher with interests in both applied and theoretical questions in animal ethics and currently postdoctoral researcher at the Messerli Research Institute, University of Veterinary Medicine, Vienna.

• Claudia is an animal studies scholar and also founder and host of The Animal Turn and Animal Highlight podcasts. She is interested in urban animal histories and futures.

• Kathy is a trained animal keeper, has been involved in bat rehabilitation since 2011 and serves as chairlady for the Austrian Bat Station, a shelter exclusively for bats.

• We talk about the significance of encountering urban animals, the many ways of “knowing your bats”, and more exciting work this project has already inspired.

Common noctule aka Großer Abendsegler (Nyctalus noctula), Copyright Mathias Swoboda

Hi all, thanks for agreeing to do this interview! I think it’s fair to say that humans have an ambivalent relationship with bats. People admire, but also fear them – Batman comes to mind, but also Dracula. Yet most people have few encounters with this flying mammal. How about you?

Konstantin & Claudia: It is common to see bats in the summer evenings zigzagging the sky to capture insects. Whether it is bats darting under the bridges that cross the Donau or circling above lamps in the Prater – when dusk hits, the bats get busy.

I (Konstantin) once had an encounter with one of Vienna’s bats: on a hot July evening, I found a severely dehydrated bat on the ground. Summers in Vienna can be very hot and dry, and the area was full of concrete, leaving the animal unable to move. I thought a bat isn’t supposed to be on the ground and likely needs assistance. I called Vienna’s wild animal emergency hotline, which provided instructions on how to properly rescue the bat. Following their advice, I offered the bat water from a bottle cap, which she (or he?) eagerly drank. She then spent the night in an old shoebox. She was very active and surprisingly noisy for an animal weighing only about 5 to 30 grams (which is the weight range for native species in Vienna).

This encounter didn’t reveal something I didn’t already know, but it rendered inescapably palpable to me the fact that we share urban spaces with other vulnerable beings, whose life quality severely depends on how we choose to build “our” habitats, and on our willingness to assist.

The Austrian Bat Station is really special in this regard – it offers shelter and care to bats who have been injured in the city. It assists bats in need – on an entirely volunteer basis – and hopes to educate the public about these incredible animals. Their website is already a treasure trove of interesting facts, like:

• “Austria’s native bat species are insectivorous.”

• “Due to the food shortage in winter, native bats hibernate. During this time, they lower their body temperature to 1-2 degrees above the ambient temperature, causing their heart rate, breathing rate and metabolism to slow down significantly.”

• “Our native bats are able to hunt and orientate themselves using ultrasonic echolocation. They produce ultrasonic sounds with their larynx and send them out of their mouth to locate their surroundings.”

For those keen to dive deeper into the world of bat communication, I (Claudia) was lucky enough to talk to Gloriana Chaverri about bat communication on The Animal Turn and I also spoke to Amanda Bunten-Wahlberg about flying foxes on The Animal Highlight. Hopefully, we will be able to make some more interesting podcast material for this project, too.

I love it. I think there should be much more public money to support work on behalf of non-human members of mixed communities in need, but for now, I put the link to a really easy PayPal donation here. And I am curious, what does a usual day/night look like for a bat in Vienna? What challenges do they face?

Katharina: It depends on the season. In spring, bats wake from hibernation and urgently need to rebuild their fat reserves. Food is scarce, so they start hunting early in the evening, especially the females who need extra energy for pregnancy. Males, meanwhile, are more independent and roost alone.

In summer, females gather in nursery roosts to raise their young. The warm nights mean lots of insects — ideal conditions. But heavily pregnant females can struggle to fly and may fall, which makes them vulnerable, especially to cats. Once the pups are born, they start learning to fly around August or September. This is a risky time — they’re inexperienced and easy prey. Bad weather is always a danger. Several days of heavy rain can mean not enough food for mothers, which affects milk supply and the pups’ survival.

In autumn, young bats are fully flying, and migratory species from as far as Russia or Ukraine arrive in Vienna. They’re often dehydrated and exhausted after the journey. The local males, on the other hand, go into full mating mode in autumn. Each species has its own mating rituals — some more monogamous, others more harem-like. After mating, it’s all about eating again to build fat for hibernation. The cool thing is: the actual pregnancy only starts in spring, so the females can focus entirely on feeding when they wake up.

In winter, it’s all about finding the right roost and sleeping. Bats are very particular about their hibernation sites. If traditional spots are destroyed—such as old trees with the right climate inside — it’s a real problem. Sadly, tree trimming in cities often removes these vital habitats. We try to educate tree workers to check for bat presence with endoscopes before cutting, but accidents still happen every year.

How important is it to know the individual animal? And how, if it is important, do people manage? For instance, how do they know that the bat they rehabilitated and released back into the wild is doing well?

Katharina: It’s absolutely essential in rehabilitation. We need to know which bat is which, so we can return them to the location where they were found. We also do daily weight checks to track their recovery. Often, we can tell a lot about the healing process from the circumstances in which the bat was found. For example, if they were caught in a window, we have to monitor different things than we would with a cat victim.

How do we know if a bat is ready to be released? Honestly, we don’t always know for sure. What we do is only release bats when we are absolutely confident that they’re ready — that they have the best possible chances of survival. And we pay close attention to the season. We would never release a bat that still has stomach issues, for example.

We have a checklist: the bats must be able to use both feet, which they need for grooming. They have to be able to use both thumbs for climbing. They must eat mealworms, at least from tweezers. They must fly perfectly, land properly, and their echolocation has to be working. We test all of this before releasing any bat.

For juveniles, checking is even more extensive. They go through long flight training with us. They must be able to fly, land, echolocate — and they also need to be able to eat mealworms on their own, to show they can hunt independently.

We don’t raise pups in isolation. We try to make sure they don’t bond too closely with humans. Of course, the hand means food — it’s supposed to — but we make sure they also hear and interact with adult bats at the station. That way, they learn how to communicate. It’s very rare that we only have one animal of a species. With juveniles, we’re especially strict. I spend a lot of money on weather hotlines because we need three consecutive rain-free nights for a release. Conditions have to be optimal so they can hunt at night.

When we release bats — especially mothers with their pups — we try to release them together, if possible, depending on their injuries. If the mother can’t be released (say, in June, July, or August), the pups are integrated into our other juvenile groups. We always release in groups.

And we don’t just “throw them out.” We use a sheltered bat house where we provide food for two more nights after release.

Konstantin, you have helped with the release this year – we have that lovely clip that I may share.

Can you tell me about the other unexpected but rewarding work that is coming out of your site?

Sure! Yes, helping releasing bats is really special — releasing a bat is one of the most magical things I have ever experienced in my life. The day that video was taken I released a Geoffrey’s bat (Myotis emarginatus), shown in the video, and two Parti-coloured Bats (Vespertilio murinus) into freedom by the Danube in Vienna. (By the way: I may be partial, but I find bats‘ names are cooler in German: The Geoffrey‘s bat is a “Wimpernfledermaus”. There is a tendency in English to name the bats according to their “discoverer” while in German they are rather named after some salient characteristic.)

This work has made me very passionate about bats and led to related projects: Claudia, another colleague, Carlo Salzani, and I are working on a paper on bats in Vienna, and Claudia and I have submitted a research proposal on urban animals, not to mention plans for a podcast episode.

That’s fantastic, we make sure to update the website. My FAQ: What are your favourite scents?

Konstantin & Claudia: Um, well, actually this is something I (Claudia) have thought a fair bit about. And I have to say it is fire smoke. I have clear memories of walking home while doing my PhD in Canada and having the smell of smoke colour the white landscape. I want to inhale it deeply. I also love the smell of rain on hot tarmac. And cake, I love the smell of cake. Mmmmm.

Nice one, Claudia! My (Konstantin) favorite scent is the fragrance of the lilac flower.

Katharina: My favourite scent – I had to think about it for a while, too, but I think it’s the smell of baby mammals when they’re still just drinking milk. I thought about it, and it doesn’t really matter whether it’s a baby squirrel, hedgehog, horse, or bat – they all smell kind of similar.