Fieldwork on Mljet – May 2025
After more than a month in the field, we are back in Zagreb! Our group spent the end of April and mid-May doing fieldwork on Mljet. After much preparation, purchasing equipment, and designing protocols, we set off on a long journey south. We began the fieldwork by searching for meadows suitable for studying the impact of thermal heterogeneity on ant behaviour. Although Mljet is a very forested island, open habitats with colonies of the ant species Messor wasmanni are still present in the valleys. To carry out our protocol, we needed accessible meadows with a large number of colonies of this species. After visiting the locations, we decided on three meadows where we set up data loggers for recording temperature and started the protocol.
A handheld thermal camera, drone, camera, and various other tools were part of our everyday equipment for measuring temperature and monitoring ant behaviour. Some of the meadows we found had a large number of colonies from which we selected the most suitable ones for our research and then visited them daily. After a while, we became well-acquainted with these colonies and everyone decided on their favourite. Although it is the same species, we learned to expect different activity from different colonies of M. wasmanni, so the term “individual differences” became the leitmotif of this fieldtrip.
In addition to examining thermal heterogeneity and differences in activity, we also dedicated ourselves to determining the number of species in different habitats across the island. From the closed and difficult-to-access macchia of the surrounding islets to the open habitats on the rocks above the Odysseus Cave, we conducted a standardised sampling method in the transect and became acquainted with a large number of species. On the stones, we encountered fast ants of the genus Lepisiota, on trees and in fallen branches members of the genus Crematogaster, and on the meadows a large number of Messor and Tapinoma individuals.
When curious Mljet residents passed by our transect, they would wonder why were our heads tilted above the ground and why were we sucking ants with an aspirator. We explained our research area to them on several occasions, and they were both surprised and excited. From them, we learned the local names of some species and which ones they most often encounter on agricultural land. We also discovered that they generally have a positive attitude towards ants and a developed awareness of the general impact of climate change. In exchanging knowledge with the local population, we learned a lot about olive growing on Mljet, and we also got to know the fire department well. Without their help and understanding, we would not have been able to reach all locations, such as the islands of Tajnik and Moračnik, but also to set up equipment in one of the main meadows for our research on ant behaviour.
We also collected a certain number of worker ants of the Messor wasmanni colony from the research locations, as well as numerous other species, to determine the critical thermal minimum and maximum, which gives us insight into the physiology of these populations. Part of the group spent many hours measuring the minima and maxima in the thermal baths at the accommodation.
Although some days our team was split in two, at the end of the day, we would gather in the apartment and exchange experiences and news. Which colonies were active, which interesting species we met, who got stuck in the macchia, who’s got bitten by ticks, and who got sunburned – we will remember all this while we process the large quantity of data we collected in the field. With new knowledge, we will return to Mljet in September, where we will continue our research, check the data loggers and sample even more ants. Until then, we have a break from Mljetovanje, and we are remembering it through rows and columns of data!
