Last weekend Iwan and I (together with a few other volunteers) joined Alex, Daan and Wout from the Bat working group to count the bats wintering in the old war fort of Steendorp.
This is exceptional in every possible way: the fort is strictly forbidden access, it is one of the biggest (20 acres) and expensive forts ever built, and it has one of the highest densities of wintering bats in Western Europe. In most years, numbers add up to 1200 bats. Keeping into account the vast number of extra bats that are hidden away deep into cracks, it truly is a mammalian hotspot.
We spent more time counting, so I did not have hours to photograph. Yet I was very happy afterwards.
Hidden away in the vegetation, is a huge brick building built in the 19th century.
Daan in one of the endless tunnels.
Many clusters of Geoffroy’s bat (Myotis emarginatus / ingekorven vleermuis)
Daubenton’s bat wintering alone or sometimes even in clusters… (Myotis daubentonii / Watervleermuis)
Bricks are being placed to add extra holes where bats can winter. Nice to see these structures having effect!
Large cluster of Geoffroy’s bat. How many do you think there were?
Big thanks to the batworking group for letting us participate in surveying this simply superb monument, and bat heaven…