Thursday, 28 May 2026 Successfully Concluded the 5th REGALNICA Event - inventory of the European tree frog

On Saturday, May 23, 2026, the fifth edition of the traditional REGALNICA event took place, starting at the  Pr Nanetovh Promotion and Congress Center in Matavun.

 The event was organized by the Škocjan Caves Park, Slovenia, the Department of Biodiversity UP FAMNIT, and the National Institute of Biology (EKOS – Department for Organism and Ecosystem Research, NIB). Its main objective was to collect data on the occurrence of the European tree frog (Hyla arborea) in ponds across southwestern Slovenia, where this charming amphibian was once widespread and abundant.

This year’s survey brought together around 65 participants from various organizations. The largest group consisted of students, but the event also attracted experts, local and cross-border nature enthusiasts, as well as several families with children. At the beginning of the event, the organizers presented the results from the previous year and explained the fieldwork procedures. Each of the 19 survey teams, consisting of two to five members, then received information about their assigned locations. Before heading into the field, participants also enjoyed a social gathering organized by the hosts.

Between 9:00 PM and 1:00 AM, each team visited between four and eight ponds, surveying them for the presence of the target species and other amphibians. This was primarily done by listening for calling frogs, while some participants were also successful in obtaining photographic records. Altogether, the teams surveyed 129 ponds and confirmed the presence of the European tree frog at 20 locations.

Through the combination of academic expertise and a citizen science approach, the project generated valuable information that will help clarify the baseline status of local tree frog populations and support future research in the surveyed areas. The results of REGALNICA will also contribute to habitat restoration planning, particularly regarding pond restoration in the region. Preliminary findings indicate that the presence of the European tree frog in local ponds has declined significantly in recent years compared to historical records stored in the database of the Centre for Cartography of Fauna and Flora.

Given the positive response from participants, without whom such an event would not have been possible, the organizers hope that REGALNICA will continue and further develop in the years to come.