It’s about 4:30 p.m. and I am waiting at the coordinates given to me by Lara, one of my colleagues. She is an upcoming Ph.D. student at Max Planck Institute of Ornithology, and she has invited me to join them for the monitoring of bat boxes.

The location is a well-maintained park in Switzerland. People are walking around, enjoying the view of the lake, plenty of trees and open spaces for families to come and play. Some species of goats are in a small enclosure and children are feeding them or staring at them with curious eyes.

I am sitting by a giant sequoia tree. Having observed the bat boxes hanging on the tree, I have many questions about them. It is my first encounter with live bats, seeing them up close and personal.

Soon Jenna joins me; she too is an upcoming Ph.D. student at the Max Planck Institute of Ornithology in Konstanz. I tell her this is my first trip to the bat boxes and I am very excited to know everything she has to tell.

Ladders and bat boxes

Jenna takes me to a corner of the park where we pick up an extendable ladder. It is an essential tool for today’s task of monitoring the bat boxes.

Dr. Dina Dechmann is leading this group at the Max Planck Institute of Ornithology. She will be joining us to supervise the activities today. We will check all the bat boxes in the area and see how many bats we find of a specific species.

There are several species of bats in the park, but this project focuses on the common noctule (Nyctalus noctula). The bat boxes have been monitored at this location for the last six years. It’s going to be a busy day for Dr. Dina and her team, as they will be taking part in a documentary shooting after finishing with the bat box monitoring. The documentary is about nights in Germany; it involves people working at night, and of course, people working with creatures of the night. 

The bat boxes are mounted on a tree trunk at a height of 4 to 5 metres above the ground. They look like ordinary bird boxes with different openings. Bat boxes can be of varying sizes and one box may contain many bats.

I have so many questions: How do bats find these boxes? Why do they come to these boxes in the first place? In my imagination, I have mostly seen bats in dark dungeons, in old houses or inside caves. In reality, I have mostly seen them in archaic buildings in India, in some very old monuments, and in some temples carved in caves like Ajanta and Ellora in India.

We have to wait for Lara and Dina, but Jenna insists on checking out a few boxes around the meeting point. She wants to get going. I have a suspicion that she just wants to get her hands on the bats as soon as she can.

I ask her my ‘why’ and ‘how’ questions about the bat boxes, and she says there are several theories as to why bats would come to boxes, but selecting one solid scientific argument to pinpoint a reason is difficult. One of the reasons could be a lack of space, as bats like to hang in old trees and there are not many in the area anymore.

Jenna quickly sets up the ladder, climbs to the top and opens a box. If I have one tip for bat box checking, it is to avoid opening your mouth if you’re close to the opening of the box, especially if you are at the lower end of your ladder. There is random dirt, old nest material from some bird or another, poop, moss—anything can drop into your open mouth when the box opens. Jenna knows the drill, and she knows it is going to be a messy job.

Recording and monitoring

She quickly pulls out a small bat that’s hanging in the nest box. It’s a rather small species of bat, a Pipistrellus subspecies. It is not what they are looking for in their research; nevertheless, it is a good opportunity for learning more about this extraordinary species.

Jenna brings it down and shows me the little mammal on wings. She does not know what subspecies it is, so she puts it in the bag and waits for Dina to arrive.

Meanwhile, Lara arrives with the required tools for today’s monitoring, and another bachelor’s student, Joelle, also joins us. She also isn’t sure about the species of bat Jenna has found, and Dina’s expertise is needed to settle the debate.

I ask exactly what the monitoring task is and what we are going to do. Lara explains that we are going to check all the bat boxes and record details about the species of interest.

I learn that males do not migrate, and currently, the females are coming back to Switzerland for winter. In early spring, they migrate to other parts of Europe, with some going to the Netherlands. The females spend winter here, where they mate and store the sperm until spring. They migrate and produce offspring in different locations, and after this process, they return.

The team will be measuring the weight of the bats, checking their reproductive status and measuring forearm length. Additionally, they will check for the presence of parasites on the body and wings of the bats.

Mites live on the wings, and streblids live on the body, hidden in the fur. They are specialized parasites and do not have wings to fly off the bats. They are probably transferred from one bat to another during contact. Bats are social, and a bat box could have many bats inside. We found more than 10 in one.

All our measurements are recorded on a data sheet. It is my job for today, and classic paper and pencil are my tools. The data collected is used to understand the different aspects of bat behaviour and their movement patterns.

Each individual gets a unique identification tag, which allows personalized long-term monitoring. The tag is inserted under the skin of the bat. It is a passive tag, meaning that when the tag is in range of the reader (2 or 3 centimetres away) it can read the ID and display it on the screen of the sensor. Individual-based record keeping with regular box monitoring keeps tabs on which bats are visiting which boxes, and whether each bat is visiting the same area every year.

There is no way to identify the individual bats without putting a physical mark on each of them. Scientists have recently started working on methods to identify individuals by using natural features or markings on their body. In the case of a zebra or giraffe, it is easier to identify individuals through stripe or spot patterns, but with bats, it seems to be a more complicated job.

So what exactly do we study?

The bats eat insects and fruit and can tell us a lot about changes in the ecology around us. Large-scale movements allow us to map the areas used by these animals and take rightful protection measures. It is also important to understand the role of these animals in spreading diseases. Unfortunately, popular beliefs are negative regarding bats, and many are driven away from their home territories.

Dina joins us and quickly divides the work between two teams. First, we will go out and collect bats from several boxes, and then bring them to the van. Then, each bat will be processed (data collection), and a passive tag will be inserted under the skin if the bat is a first-timer. Jenna and I will check on a section, while Lara and Joelle will check another section.

A noticeable thing about the team is their love and affection for these creatures.

We show Dina the small bat we had captured earlier with Jenna. Dina quickly takes the identification book and reads out the detailed description about features of the ears and patterns on the wing membrane for different subspecies of bats.

She knows the answer, but is taking time to groom her students, as it is an important part of the process. The student must learn to understand the complex scientific terms and correctly identify the species. This is very important in cases of rare and endangered species.

They identify the species as Pipistrellus nathusii. Bats have vocalization in an ultrasonic range that humans cannot hear. However, they can make sounds in the audible range for humans, a click-like high-pitched sound, which can be annoying to human ears at a close range.

Fun Fact: The wings are actually membranes that join the fingers. It is amazing to see how evolution has shaped different species in different ways. Once you start observing different mammals, similarities in their structure with humans are strikingly clear, and the modifications are fascinating.

We start checking boxes

Jenna and I start checking some boxes while the sun is setting. She says it is fun to work at this time of the day—well beyond 17:00 [5 p.m.]. It is the golden hour of the day; the sun will be setting soon, and the golden light is blending with the green colour, making the leaves and the grass glow.

The sky is clear and gigantic peaks of the Alps are visible on the other side of the lake. I think it is reasonable to enjoy the setting while opening bat boxes and constantly avoiding the random dirt falling from trees and boxes.

Wildlife researchers have to battle harsh climatic conditions and work at odd hours. This research involves many failures; for example, in the first round of checking five to 10 boxes, we mostly find bats from the Pipistrellus subspecies that we do not want to monitor today.

Jenna tells me about her work in Panama with the bats. She tells me about different species of bats in Panama and related stories. In Panama, she learned about the work of Dr. Dina and Professor Dr. Martin Wikelski—the director of the Max Planck Institute for Ornithology—which brought her from the U.S. to Germany.

Currently, she is assisting Dina with monitoring work in Konstanz, which will be continued by Lara from this year on as part of her Ph.D. thesis. She has been bitten many times while handling bats; once again, part of the job.

Dealing with bats is tricky and a researcher could contract diseases like rabies, so it is important to avoid unnecessary physical contact with the animals. I am not allowed to touch the animals, yet I can look at them up close and at best, take pictures. This arrangement works for me, as I have not yet had my rabies vaccination.

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