In June 2023 Thomas Szczepaniak sent information about beaver signs observed along the Dera river and the Márton swamp. In this area, he found burrows, collapsed burrows, signs of gnawing and a beaver dam, as the evidences of beaver presence.

„The interesting thing is that the beavers seems to have colonized both the river and the swamp next to it. Given the number of holes there are probably several individuals although I could only see one at a time. The dam rises the river level but has no incidence on the swamp water level.

Although blocking the stream may have consequence for fields located downstream?”

Beaver dams help to retain water. Due the increase of the amount of surface water and groundwater, water regime of the areawill change markedly. As positive effects, wetlands could be restored or created, and the amount of hay may increase in the nearby lands.