Text & photographs © Conor Kelleher

Built by the Germans prior to and during World War II, Nietoperek Bat Reserve is part of the once massive Miedzyrzecz Fortified Front that formed the eastern border of Germany. The fortifications are now in Poland. This series of bunkers and underground tunnels, stretching for 30 kilometres, were never completed. Only 60% of the original plans were constructed. However, the existing tunnels and bunkers are a testament to incredible engineering and determination on behalf of the German leadership of the time to protect the country's eastern boundary. Many of the bunkers are separate to the underground system and contain up to 40 rooms, with lift shafts etc. The main tunnels contained a two-track, electric railway with many stations along the route. The walls were constructed of 3 metres of reinforced concrete and the cupolas of the bunkers were covered with 0.5 metres of steel. This insured survival from artillery and there is ample evidence to the visitor as direct shell hits are still visible which hardly dented the structure.

Cupolas surmounting a bunker

Although built at huge expense, using labour from prison camps, the Front only held for three days when the Red Army crossed Poland in January and February 1945. At the end of the war, the Russians chose not to retreat from Poland and occupied the country until their withdrawal in 1993. During the intervening years, the fortifications were vandalised both by the local people trying to make a living selling the contents as scrap and by the Russians who used the bunkers for target practice. The tunnels are now stripped of all they contained. This was encouraged by rumours of Nazi treasure hidden in secret rooms. Some gold and art works were discovered but there are still those who believe that the famous Russian 'Amber Room' is contained within the walls of these tunnels.

The entrance to the 'Tourist Road'

In the 1980's, the then communist Polish government decided to use the tunnels as a dumping ground for nuclear waste. This prompted a national, and international, outcry from bat workers, academics and wildlife enthusiasts for it was known that the tunnels were used by large numbers of bats during the winter months. This is, however, an understatement, as the tunnels and bunkers are home to some of the rarest of European bat species and numbers frequently exceed 30,000 animals. These bats come to Nietoperek from across Poland, Germany and the Czech Republic. Due to the interest shown by concerned groups, the plans for nuclear dumping were abandoned and, subsequently, the part of the system with the greatest bat numbers was declared a nature reserve. The reserve area has since increased to include important foraging habitat surrounding the undergrounds.

Russian tank and anti-tank fortifications

However, the reserve is constantly under threat from developers who want to increase tourism to the area and there is also much local politics involved as different interests seek to make a living from the fortifications.

'Dragon's teeth' - anti-tank fortifications

I was able to observe this at first hand when I visited the area recently. A large area of native shrubs and trees had been cleared in the protected area just to enhance the view for tourists! The battle of Nietoperek is continuing by Polish bat workers to ensure the survival of bats who have no voice of their own. I met several of these enthusiastic people during my stay in Poland. Their commitment and energy is contagious and both traits are needed if one is to explore the undergrounds.

The entrance to the undergrounds

The first thing to ensure before you enter the tunnel system is that you have plenty of charge in your torch and enough batteries to last 10 hours! You must also wear adequate, comfortable, footwear as the tunnels are flooded in places and many kilometres will be covered under ground. The tunnels are treacherous as they contain many open manholes and deep shafts that are covered by water. The walker must be constantly vigilant and the 'point' person gives warning to those behind of any holes. A shouted 'Dziura', the Polish for hole, is an abiding memory of a walk in the undergrounds of Nietoperek!

'Nietoperek Nature Reserve'

During this visit, several studies were being performed on the bats. Members of the group came from two different Polish universities - Wroclaw and Torun and each had their own work. The above ground bunkers were surveyed for bats, temperature and body mass details were recorded on bats in the main system and corpses were collected for later study. This work was intensive but rewarding as it led to the observation of many different species.

Mixed cluster of c400 Myotis species

During my week at the site, the group encountered some of the continent's rarest bat species, including; Greater Mouse-eared (Myotis myotis), Barbastelle (Barbastella barbastellus), Bechstein's (Myotis bechsteini), Whiskered (Myotis mystacinus), Natterer's (Myotis nattereri), Pond (Myotis dasycneme), Daubenton's (Myotis daubentonii), brown long-eared (Plecotus auritus), Brandt's (Myotis brandtii), Northern (Eptesicus nilsonii) and Serotine (Eptesicus serotinus). It was truly amazing to see congregations of such rarities. The importance of this site is immense and cannot be overstated.

Mickal, Peter and Tomek readying the equipment!

Each species chooses a different area within the undergrounds to over winter. Barbastelles seek the coldest areas, near entrances, at 3 degrees, whereas species like Daubenton's bats like warmer areas up to 9 degrees. Daubenton's bats are the most numerous species within the tunnels, often exceeding 9,000 individuals. Upwards of 30 volunteers undertake a count of the entire under ground system in January. The results of this count are an under estimate as all the bats are not visible, being hidden in pipes, niches etc. So the total number of animals using the system will never be known.

Mouse-eared bat cluster on tunnel ceiling

Tourists are encouraged to visit the tunnels during the summer months when the bats are not present. The use of the system, by bats, is highlighted to visitors and it forms part of the educational tours organised locally. There is a serious threat to the bat reserve by local tourist groups who want access to the undergrounds throughout the year. This is unrealistic as there is no tourism to the area in winter, however, this is not preventing local politicians encroaching on the reserve. These moves are being carefully monitored. Any noted, or potential, risks to the reserve, through the use of the 'Tourist Road', are being contested by bat workers with reference to the 'Nietoperek Management Plan'. This document was drafted to ensure the continued safety of the reserve and its surroundings.

Gosia and Tomek weighing a bat

The on-going protection of this unique site, both above and below ground, must be ensured. It is difficult to see any good that ever came out of Hitler's reign but this reserve is one positive result, albeit by default. The indigenous bat workers of Poland should not be left on their own when it comes to providing a voice for the bats whose survival depends on this site. To paraphrase the 'Old Order'; "Bat workers of the world unite, you have nothing to lose but your bio-diversity".

Mickal, Asia, Peter, Gosia, Yanuk and Tomek take a break!


My thanks to the Polish bat workers and other people that I met during my stay in Nietoperek, in particular, Tomek, Mickal, Gosia, Asia, Peter, Yanuk, Anna and Robert. No one could ask for more welcoming or generous hosts.