10/7/2023 0 Comments Bright dusk skyIf they hunt for food, they fly slower and with much stronger curves and turns. When the bats commute between areas, they fly very fast and almost straight with only small turning angles. Using the flight speed and turning angles between successive GPS positions, they differentiated between commuting and foraging flights. The researchers began recording the GPS positions of the animals half an hour before sunset and repeated this every 30 seconds throughout the night. Some even fly out of the city into the countryside and return before dusk.įor their investigations, the scientists equipped 20 common noctules with miniature GPS transmitters. For commuting, they prefer dark corridors such as forests, unlit city parks or waterways. In contrast, common noctule bats avoid artificial light when they commute between different feeding areas and their daytime roosts. Of course, this also attracts some bats who like to take advantage of this rich food supply”. Voigt and his colleagues suspect that many insects are present at these sites when insects are lured by the street lamps at rivers, channels, and lakes: “Particularly near water bodies, swarms of insects can be found buzzing around lanterns after they have developed from larval stages into adult insects. However, bats only hunt at street lights when water bodies or areas with high vegetation cover are nearby. Overall, however, they prefer the dark areas of the city,” says Christian Voigt, head of the Department of Evolutionary Ecology at Leibniz-IZW and first author of the paper. “We noticed that some bats searched for food in areas with artificial light, especially along watercourses. These are the areas of the city that the bats prefer to hunt. They were particularly interested in whether bats use illuminated areas for commuting and foraging or whether they switched to dark habitats. The international research team led by experts from the Leibniz-IZW investigated how common noctule bats react to various features of the urban landscape in the larger Berlin metropolitan area, in particular to artificial light at night. The results are published in the journal “Landscape Ecology.” Dark corridors such as city forests, parks or watercourses, on the other hand, are of great importance for commuting and foraging. The metropolitan area of Berlin is therefore mostly unsuitable as a habitat for bats. They show that common noctules avoid brightly lit, built-up areas. But how do nocturnal animals such as bats respond to the illuminated urban landscape? In a recent study, scientists from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), together with German and international colleagues, equipped common noctule bats (Nyctalus noctula) with mini GPS transmitters and recorded their trajectories in the sky above Berlin. People can hardly imagine a city without night-time street lighting. The metropolitan area of Berlin is mostly unsuitable as a habitat for bats because of the bright night sky. Credit: ISS047-E-29989 courtesy of the Image Science & Analysis
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