This article was originally published on the lilieci.ro project website, and is also available to read in Romanian, Serbian and Hungarian.

If you ever stood on the banks of the River Danube in the Iron Gates region of Romania and looked towards the Serbian shore, it seems to be within arm’s reach. At some points, the Danube is just 150-200 metres wide. Now imagine that bats fly. They fly fast and with a purpose. They know the landscape better than anyone else. Country borders? Meaningless! A night-feast on the insects on the other side? Count us in!

Yes, bats migrate between Serbia and Romania, sometimes across the Danube. They spend the summer in Serbia, but hibernate in the caves of southwestern Romania. The first such observations were performed in 2014, in the caves of the Semenic – Carașului Gorge National Park. Since then, Serbian bats were observed to hibernate also in two other protected areas of Romania: the Nerei Gorge – Beușnița National Park and the Iron Gates Natural Park.

So far so good. Now a little bit of background.

All five European horseshoe bat (Rhinolophus) species are threatened by multiple factors, including direct disturbance in their roosts, which can be caves or buildings. Because of these factors, all five species have decreasing populations according to the IUCN. Méhely’s horseshoe bat (Rhinolophus mehelyi) is still classified as vulnerable. Blasius’s horseshoe bat (Rhinolophus blasii) is still the rarest horseshoe bat in Europe. The Iron Gates region is a sub-Mediterranean biodiversity hotspot, with several huge bat colonies of continental importance, both in Romania and Serbia.

However, despite the importance and size of these colonies, not much active bat conservation has been done here. In 2014-2015, a project aimed at improving the conservation of Rhinolophus species took place in the region, but only in Romania. New colonies were discovered, including that of Méhely’s horseshoe bat. Recommendations for protecting these colonies were made to protected areas. The project was funded by the Conservation Leadership Programme (CLP), a partnership of global NGOs aimed at addressing the changing conservation needs of the modern world.

Enter 2018, when during a project funded by the Columbus Zoo and Aquarium, and aimed at cavers, the Romanian team captured in the Semenic area a bent-winged bat (Miniopterus schreibersii), carrying a Serbian ring. Apparently, not only Rhinolophus species migrate between Serbia and Romania. More and more colonies were discovered, but their protection still did not reflect their continental importance.

Fast forward to winter 2021.

Full-blown pandemic. The media blaming bats or other wildlife. People prioritizing toilet paper and piling up food. But the bat researchers of Romania and Serbia have other business. They implement a new project in the Banat region. The Romanian-based Centre for Bat Research and Conservation, and Myotis Bat Conservation Group work together with Serbian bat experts from the Natural History Museum of Belgrade. They have just finished the winter fieldwork. All this in the frame of a project financed yet again by CLP, fittingly entitled: Transboundary conservation of horseshoe bats in the Romanian-Serbian Iron Gates.

For the first time since the 2014 discovery of bats carrying Serbian rings in Romanian caves, the bat researchers of the two countries now undertake synchronous fieldwork on both sides of the Danube. Their goal: to improve the conservation status of horseshoe bats in this whole region. Why? Because if there is indeed a significant bat migration between Serbia and Romania, then protecting colonies on just one side of the Danube is not enough. In order to reach such a goal in the future, the project will create the primary elements needed for such a transboundary conservation: (1) accurate scientific data about bat migration in the region, (2) concrete conservation actions at the most important bat caves, and (3) an engaged and well-informed public on both sides of the Danube.

Already during this winter fieldwork, the teams have made discoveries of new Rhinolophus colonies, and added to the growing number of Serbian bats with rings observed wintering in Romanian sites. This continued in May, during the spring fieldwork, where we discovered a new transitory colony of about 500 bats (R. ferrumequinum, R. euryale and maybe R. blasii), and recorded ultrasounds of Rhinolophus species on the islands along the Danube. Results are encouraging, to say the least. Currently, the team is preparing for the summer monitoring of nursery colonies in the Iron Gates region, while also searching for previously unchecked sites and new colonies. In all, already more than 50 sites have been either monitored (with known colonies) or checked for new colonies.

Implemented in 2020-2022, the project targets six major protected areas in the Iron Gates region, but also areas adjacent to these, as they may harbour bat colonies in buildings. Of course, the project could not be implemented without the help of local protected areas, as well as the caver clubs, which have specific knowledge about rarely visited caves. We are grateful for their efforts!

Visit the Lilieci.ro Facebook page for more information and snapshots from the project.