A study in Madrid has shown that the distribution of green spaces directly affects the number of bats, and thus, the control of urban pests. For the capital’s residents, this is not just an environmental issue—it’s about health, safety, and quality of life. The new data could change the approach to urban development and the allocation of green areas.
Where bats live
Despite their small size—some species weigh just 3–8 grams—bats play a key role in the city ecosystem. According to El Pais, researchers Lidia Mayordomo and William Carvalho from Universidad Autónoma de Madrid found that neighborhoods with more greenery have noticeably more bats. This is particularly evident in wealthier areas, where parks and gardens cover significant portions of land. In contrast, less affluent districts have fewer green spaces, impacting biodiversity and residents’ comfort levels.
Scientists note that bats not only help maintain natural balance but also provide direct benefits to humans. They actively eliminate insect pests, including mosquitoes that can carry dangerous viruses and pine processionary caterpillars, which pose risks to pets. As climate change intensifies and harmful insects expand their habitats, this function becomes increasingly important.
Study results
During the study, experts found that bat diversity and activity reach their highest levels when at least 43% of the urban area is covered with vegetation. This conclusion was based on data gathered by 77 ultrasonic sensors placed throughout Madrid in the summer of 2023. The research showed that even small green ‘oases’ between buildings can significantly boost bat populations if there are enough of them.
Six species of bats live in Spain’s capital, including Pipistrellus pipistrellus and Nóctulo. Contrary to common myths, most bats do not feed on blood—they prefer insects. In the city, bats often use buildings and other structures for shelter, as natural hiding places are becoming increasingly scarce.
Challenges and issues
Researchers believe that the uneven distribution of green spaces leads to environmental inequality between neighborhoods. Access to parks and gardens should be a right for every resident, not a privilege. However, as experts point out, city authorities often overlook scientific advice when planning new projects. Even successful initiatives, such as the restoration of natural habitats along the Manzanares River, can be undermined by tree felling or excessive holiday lighting.
In recent years, Madrid has seen an increase in the appearance of new mosquito species previously unseen in the region. This is linked to climate change and a decrease in the natural predators of insects. Bats are capable of curbing pest spread, but for this they require suitable conditions for living and breeding.
Impact on city policy
Interest in the research has come not only from Spanish specialists, but also from experts abroad. As El Pais reports, representatives from the municipality of Quebec have already reached out to the study’s authors for advice on implementing similar measures in their cities. In Madrid, however, scientists believe there is still a lack of political will for systemic change. With political uncertainty and potential cuts to environmental project funding, the future of such initiatives remains unclear.
In recent years, discussions on the role of urban green spaces in combating the effects of climate change have become more frequent in Spain. Barcelona and Valencia are launching projects to create new parks and restore natural areas. There have also been attempts in Madrid to increase green spaces, but uneven resource allocation and insufficient attention to scientific data hinder sustainable results. In other European capitals, similar research has already laid the groundwork for new urban planning standards.
