Bat excursion

For most people, night time marks the end of a day, but for some creatures, it is only just the beginning. If you think urban centres are devoid of wildlife, you might want to reconsider, for its wild inhabitants might just be waiting for the fall of night to roam about. Bats are among the most iconic but virtually undetected nocturnal city dwellers. Circa 21 species of bats can be found in The Netherlands alone and some of them might even call your roof home! As an exciting way to start the month, we had the pleasure to join ecologist and bat expert Ilco van Woersem in a nocturnal excursion through the residential suburbia of Utrecht in search of the elusive ¨flying mice¨. Equipped with bat detectors, small devices that detect the ultrasounds produced by bats, we followed Ilco into a residential neighbourhood and, lucky for us, he knew exactly where to find the bats. According to Ilco van Woersem, Dutch houses have small gaps in their structures, where bats can easily fit through. It is no wonder they chose someone´s roof to make their nest! Right after dusk the first inhabitant emerged. Our task? Counting them. It wasn’t easy but, in total, we were able to detect c.a. 42 individuals emerging from the roost site. This was a roost of the common pipistrelle (Pipistrellus pipistrellus), one of the most abundant species in The Netherlands. But the evening was far from over. From the house, we took to the wonderful Beatrix Park, where we were able to hear, and in some cases see, other bat species. One notable species being the water or Daubenton´s bat (Myotis daubentonii). The water bat is most notable for occupying a distinct foraging niche since it only feeds above water bodies. We were also delighted with the presence of two other bat species during our walk, Pipistrellus nathusii and Eptesicus serotinus, both with very distinctive vocalizations that we were able to recognize with the bat detectors. Unfortunately time flies, and it was time to head home. Our participants were able to return with a few bat trivia up their sleeves. So now you know, next time you take a walk at night, look at the skies! Thank you all for participating and we hope to see you again soon! By Monica Vidal