In Zurich they not only discovered the most bats in terms of numbers, but also the most different species, as the Federal Research Institute for Forests, Snow and Landscape (WSL) announced on Wednesday.
Study leader Martin Obrist, nature conservation biologist and bat expert at WSL, suspects that this is due to the numerous natural areas and forests near the city. According to Obrist, nearby bodies of water also proved to be an important factor for the bats’ survival. These served the nocturnal animals both as a water source and as a hunting area.
Millions of bat calls evaluated
As part of a European research program, the team is investigating how green spaces affect bat diversity. In total, they recorded five million echolocation calls from flying bats with special measuring devices. The different bat species can be distinguished on the basis of the characteristic calls.
The researchers also used light traps to determine the number and species diversity of nocturnal flying insects. Accordingly, Zurich also had the highest diversity and frequency of insects. This increased with the increasing area of urban green spaces. And: “It is of great importance that green spaces do not represent individual isolated islands, but rather form a network within the city,” said Obrist.
Pipistrelle feels good
The researchers found the pipistrelle most frequently in the three cities examined (Pipistrellus pipistrellus), which tolerates artificial light well. This also attracts many nocturnal insects that bats eat as a source of food.
On the other hand, light-shy bat species such as the great mouse-eared bat (Myotis myotis) or the brown long-eared (Plecotus auritus) are losing their habitats due to increasing light pollution in cities. This explains the researchers’ low bat diversity in Paris and Antwerp.
The artificial lighting must definitely be reduced in order to promote the nocturnal biodiversity in the cities, said Obrist. Where this is impossible, LED lights that can be dimmed and controlled could help. Because: “The lights then only emit the full amount of light when needed, for example when a car drives past,” says the nature conservation biologist.
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