Nearly 4,000 tourists have visited the Biserna cave this year. This is shown by the data from the spring and autumn opening period of the tourist site. November 25 and 26 are the last weekends this autumn in which the cave will be open, and from November 27 until spring the site will be closed.
The restriction was introduced to protect the cave's inhabitants - bats - during their winter sleep. They hibernate to survive without food until spring. Disturbance during this period can cause their energy reserves to run out and they may not survive until the end of winter. 14 species of bats are found in the cave and are currently forming their winter colonies.
The cave will welcome tourists again in April next year.
The Directorate of the Shumen Plateau Nature Park maintains the current regulation for entry with advance registration. This is done on working days by calling the Directorate's phones and on site at the Park's Administrative Center. "Biserna" can be reached via two pedestrian routes, along which signposts have been placed.