This website has been automatically translated by DeepL. When accessing the pages, personal data remains anonymous, as no data is transmitted to the service provider. The translated content is stored locally on the City of Bonn's web server and delivered directly from there. However, it is possible that machine translations do not fully correspond to the original text. The City of Bonn therefore accepts no liability for the accuracy, completeness and up-to-dateness of the translations.
We use cookies to ensure that we give you the best experience on our website www.bonn.de. Technically necessary cookies are set for the operation of the site. In addition, you can allow cookies for statistical purposes and thus help us to constantly improve the user-friendliness of bonn.de. You can adjust the data protection settings at any time or agree to all cookies directly.
Both individual old trees and groups of trees (so-called forest islands) are important habitats and retreats for many animal species in the city. Furthermore, they have a positive effect on the microclimate (shading, oxygen production) and, last but not least, also delight us humans with their calming effect.
Nuthatches and tits depend on tree hollows for nesting and birds such as treecreepers appreciate gnarled bark to find insects. For woodpeckers, owls, bats and squirrels, large, old trees with their holes and crevices are also essential for survival as feeding and breeding grounds. Even lichens and semi-parasitic plants such as white mistletoe (Viscum album) use old trees as a habitat.
Did you know?
Why an old tree cannot be replaced by planting young trees?
Winter lime tree.
If an old tree is felled, it is almost impossible to compensate for its loss. Although young trees are planted to replace them, this is not the same. Old trees have an expansive crown with thousands of leaves. Their oxygen production and attractiveness for animal and insect species is correspondingly high. A small tree has only a small leaf area and cannot keep up with this.
Tree hollows and the gnarled bark of a tree only develop in old age, depending on the tree species. Many birds and mammals use the cavities as breeding and hibernation sites. The more cracks, crevices and knobs the bark has, the better - hundreds of insect species live on an old oak tree! Old, dead branches in the tree are an important detail. This is where beetle larvae live in the wood and the woodpecker prefers them to build its burrows.
One of the endangered species and the largest of the 24 bat species found in Germany - the common noctule bat (Nyctalus noctula) - is also found in Bonn. Originally native to forests, this species has also conquered the city - as long as there are enough tree hollows for roosting and hibernation.
Bats are mammals and only have one or at most two young per year. The young are nursed for weeks in pure "mother-child" groups, which are set up in large tree hollows. As the common noctule starts its hunt for insects soon after sunset, it is easy to observe.
Naturefriends tip
If you want to preserve and promote native plant diversity, you should choose native tree species for your garden. A pile of leaves is a welcome hibernation hiding place for insects and hedgehogs in the fall/winter. If a tree has to be felled, part of the trunk can be left as dead wood as a compromise, so that beetle larvae and other insects can find a habitat. It is not uncommon for great spotted woodpeckers to carpenter their burrows into tree trunks in the city.
If the garden is too small for large trees, insects living in and on the wood are happy to find a pile of dead wood. The highly endangered stag beetle (Lucanus cervus), which is also found in Bonn and is our largest native beetle, lays its eggs in dead oak and fruit wood, where the larvae develop over several years.
