An examination conducted in the Devetashka Cave confirmed the concerns of the environmentalists

An examination conducted in the Devetashka Cave confirmed the concerns of the environmentalists

The examination was carried out by experts of the Bat Research and Conservation Center at NMNH Sofia, BAS.
The aim of the examination was to compile an expert assessment on the state of the bat colonies, as practically the experts of RIEW Pleven, who are legally entitled to control the actions, could not possibly reach the depths of the cave. The expert team has managed to reach the first threshold of the Devetashka Cave, where the bat colonies are typically located.

The experts confirmed the already received information for the installation of temporary constructions for the aims of the production and the shooting of the movie. Despite the conditions and explicit ban enforced by RIEW, the examination reported that the constructions do reach the dark side of the cave.

The examination also confirmed the suspected intense noise pollution, which experts claim to reach “alarmingly high levels”.

The noise, generated by the shooting preparations, could be clearly heard even in the most distant parts of the underground galleries, where the bat colonies are usually located” – says Antonia Hubancheva – one of the experts who took part in the examination.

According to the biologists, noise pollution and the periodic presence of workers in the semi-dark and the dark parts of the main gallery have forced the bats to move towards the inner parts of the cave, which are not suitable for winter roost due to their higher temperature.

The high noise levels cause constant disturbance of the bat colonies. Therefore bats are kept in a semi-active state instead of hibernation. Because of this, they are spending significantly more energy and are untimely exhausting their food reserves. Their disturbance in the beginning of winter might cost the lives of hundreds of individuals if their fat reserves deplete to critical levels.

Wintering bats have been found by experts, who however claim that the colonies currently account for less numbers as compared to previous years.
For example, in the winter of 2010 – 2011 the colony was estimated at about 35 000 individuals. Currently, the cave is inhabited by barely some 8 600 individuals. The maximum numbers recorded in the cave reach up to 60 000 individuals.

Unfortunately the expert assessment of the impact of the shootings is highly impeded, as no preliminary base assessments have been done before the shooting started. At the same time the finding of dead individuals is impossible, as the bat colonies are roosting over an underground river.

Dead individuals have NOT been found, as the bat colonies are roosting over an underground river, which carries everything out. In addition to that, the cave is rich in crustaceans, which feed on the carcass of the fallen bats. The lack of a more complete and adequate analysis of the situation is exacerbated by the fact that no preliminary assessment of the populations have been done prior to the shootings.

Movie and other productions of such scale and duration inevitably decrease the quality of the underground habitats. The frequent presence of people, the noise and light pollution lead to constant disturbance and pose significant negative impact on the bat colonies, especially during winter” summarized Nikolay Simov from the Natural History Museum at BAS – Sofia.

The expert report has been submitted to the National Service for Protection of Nature, the Ministry of Environment and Waters, RIEW Pleven,the Natural History Museum and the response of the relevant authorities is expected. We are also going to contact various international organizations working on bat conservation.

Source of information: Bat Research and Conservation Center at NMNH Sofia, BAS

Photo credit: Antonia Hubancheva and Svilen Delchev

For more information, please contact:
Bat Research and Conservation Center at NMNH Sofia, BAS – Nikolay Simov: +359 899 361474, Boyan Petrov: +359 893 322107
Green Balkans NGO – Elena Stoeva: е-mail:, +359 887 574699