Field | Žumberak Mountains 2021

Hello everyone, and, after a longer break, welcome back to my blog! As the title itself suggests, I was a part of another BIUS field trip, which was again located at the Žumberak Mountains. For the adventures from the previous year, click here and here.

Quick reminder:
BIUS is an association that gathers many Biology students from our department and focuses mainly on field trips, excursions, and expert lectures, all in order to complement and expand our Biology-related knowledge about certain topics. BIUS is also a publisher behind In Vivo Magazine, for which I served as editor-in-chief and I am now an adviser.

Initially, I planned to write this post as soon as I came back, back in May, but I felt rather overwhelmed by everything in my life, especially health wise. I decided to postpone all of my posts, both on this blog and social media, because I just didn’t have enough energy to dedicate myself to creating content in a way I thought I should.

If you read my previous posts about Žumberak, you already know that, despite wanting to spend my life working in a lab, I also like to explore nature. During the last field trip, I was part of the Crustacean group, and this year, I was part of a Butterfly group, although I don’t know that much about either of these topics. However, one of my main reasons to go to excursions is to learn and experience new things, connect with other people, and make great memories. And I must say, I had wonderful four days. I would also like to thank to two other members of our group, Filip and Ivan, for selflessly sharing their knowledge with me and having patience to answer all my questions!

Frist photo: Asplenium scolopendrium (hart’s-tongue fern) sprouts. Forests were full of these and, honestly, I was feeling like I was a character in a fantasy novel, surrounded by magical plants.
Second photo: A bee and a wild orchid. I must admit that I'm very proud of this photo 🙂
Third photo: Caddisflies! Every stream was full of the caddisfly larvae; you might think these are just some silly rocks, but those are actually insects of the order Trichoptera, who make these protective cases in their larval stage.

I arrived at Sunday, just a little bit before noon, and immediately joined my group; they were strolling down the road, mostly checking environment and inspecting passing butterflies. My main task was taking photos, especially if anyone caught a butterfly. The Butterfly group itself was only recently revived, after Filip showed amazing initiative and interest in butterflies, so we were all actually new to the group, trying our best to wave our little nets. Our main tasks were:

  • confirm the already recorded species of day butterflies
  • investigate and record species of night butterflies, which are not very well known in this area

I should immediately note that, despite being successful at both tasks, we noticed an alarmingly small number of butterflies and insects in general, especially for that time of the year. I am honestly not sure what is to blame; we had a weird winter that jumped right into high summer temperatures and our country is, sadly, generally not very preoccupied with the protection of nature, species, and habitats.
There were also fun moments, with Ivan very decidedly running after every butterfly in sight. Also, the Botany group brought us a little caterpillar for determination, which Filip then successfully nurtured to the butterfly stage, in order to determine the species.

Zoom in photo of FIlip's hand expertly holding a butterfly (scarce swallowtail).
Iphiclides podalirius (scarce swallowtail)

A bug (Meloe sp) is seen in the middle of a picture, standing on a fallen leaf, surrounded by green grass and sprouts.

After returning to the camp that same day, I investigated an area around it, with my friend Paula, who used to be a leader of a Beetles group (and is now leading Marine Biology). She was, naturally, much better than me in spotting hidden insects and even caught some water newts after we stumbled upon a puddle. It was such a fun and interesting day, and my only regret was forgetting my straw-hat at home, because the sun was really too strong for my taste.

(Photo: Meloe sp, probably violaceus)


My next day was, however, my favourite experience of the whole trip, because I joined the Biospeleology group and went caving! The last time I visited a cave before this was in 2019, and I must admit, I missed it so much; that specific smell of the cave air, wearing three layers of clothes, fixing my helmet all the time, and walking through impassable terrain. Wait, scratch that last one, I never miss walking on the extremely narrow mud path through the forest, holding onto branches we are passing on the way, barely catching my breath, trying to finally reach the cave entrance. Luckily, everyone in the group was completely understanding and wasn’t imposing any type of time restrictions. Three of us were students, but we also had an expert mentor, who was so kind, patiently answering our questions.

First photo: Mia & Martina looking for spiders
Second photo: Grasshopper sp.
Third photo: A flying insect, perhaps a mosquito, starting to get... Calcified? Mineralized? I'm honestly not sure what is the right word to use here.

The cave in question is called Zidane pećine (roughly translated as Masonry caves), and it’s a cave you can access without the ropes (helmets and speleo overalls are a must). The main task of the group was to collect various insects and bugs that might live in the cave, mainly spiders. Now, the focus was on the creatures that might permanently live in the cave, and not on the ones that only sometimes enter the cave in search for a hiding place. I was, unsurprisingly, mostly taking photos: of my colleagues, cave walls, and various animals inside, which include creepy grasshoppers (not their scientific name) and bats. The cave is also apparently an archaeological site, although I can’t find any verifiable information about that, apart from one mention in a blog post which states that archaeological find dates back to the 16th century and Ottoman attacks. What locals did tell us it that the cave used to be a hiding place during the wars.

Dimly lit photo of a part of the cave wall, it's partially hollowed out by the long-term effects of the dripping water.
A part of the wall inside the cave

Tuesday was a bit more challenging for me; our lovely group leader Filip decided we should check out a big meadow at a higher elevation, which doesn’t sound too bad, except the sun was plaguing me badly. However, we were hopeful we might find an interesting butterfly, but barely found any butterflies at all. As it turns out, it was simply too cold for them at that particular place. We spent the rest of the day mostly hanging around the camp, until evening, when it was time for the night hunt. And yes, it was as cool as it sounds. Around 10pm, a huge group of us gathered a bit further from the camp, in order to observe, and in some instances catch, bugs that are active during the night. To accomplish this, Mladen, mentor of the Beetles group, put up two pyramids, which are made of a metal construction with a simple fabric thrown over it, and a UV light in the middle of it. (Mladen also politely measured a safe distances for me, in order not to be harmed by the UV light, although I have to admit, I purposely got quite close couple of times, in order to take pictures). One of the pyramids was erected next to the road, and another couple of hundreds meters away, near the bank of a stream. It was really fun going back and forth, and taking pictures of all the insects and spiders we found on the road. This experience was also very educational for me, not only because this was my first night hunt, but also because I was surrounded by experts who gladly shared their vast knowledge about beetles, spiders, moths, caddisflies, and mosquitoes.

A night butterfly (moth) on a fabric of the pyramid; the front side is seen, showing moth's head, antennas, front legs, and a part of the body.
A beautiful night butterfly

My last day was Wednesday, and as a group, we honestly didn’t have much to do, due to changeable weather and very strong winds. We visited a bio-park nearby, where we saw llamas and walked next to donkeys and donkey-hybrids. It was overall a fun ordeal and we didn’t understand why are we the only visitors there. After a quick search on our phones, we realized that the park was a part of a small ecological scandal last year, so we left. The second part of the day was spent with the Crustacean group; together, we visited a beautiful creek, which was much bigger than I expected. Members of the Crustacean group were setting up traps, similar to the ones I was writing about last year, while the rest of us just walked around, amazed by the nature around us.

This is me (wearing an army jacket) kneeling, almost sitting on the riverbank and taking photos of newts and tadpoles in a muddy stream.
Here, I was trying to take photos of newts and tadpoles

As I was driving home that evening, I couldn’t help but smile reminiscing about the packed experience I just had, which included not only visits to the breathtaking places, but also learning more about the tiny world around me, taking numerous photos and videos, and meeting new people.


Here you can find social media of some of the members of the Butterfly group, as well as the link to official Instagram profile of the group. I am also sharing a social media link to Paula’s Instagram, who already shared impressive photos and videos on her profile.


Three people in embrace (two men, one woman) posing, on the road in front of the trees and thicket.
The Butterfly group